Error loading C4 realnewslike dataset
Hi @danshirron, 
`c4` was updated few days back by @lhoestq. The new configs are `['en', 'en.noclean', 'en.realnewslike', 'en.webtextlike'].` You'll need to remove any older version of this dataset you previously downloaded and then run `load_dataset` again with new configuration.
## Describe the bug
Error loading C4 realnewslike dataset. Validation part mismatch

## Steps to reproduce the bug
```python
 raw_datasets = load_dataset('c4', 'realnewslike', cache_dir=model_args.cache_dir)
## Expected results
success on data loading
## Actual results
Downloading: 100%|████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████| 15.3M/15.3M [00:00<00:00, 28.1MB/s]Traceback (most recent call last):                                                                                                                                                                                                                                             
  File "run_mlm_tf.py", line 794, in <module>                                                                                                                                                                                                                                  
    main()                                                                                                                                                                                                                                                                     
  File "run_mlm_tf.py", line 425, in main                                                                                                                                                                                                                                      
    raw_datasets = load_dataset(data_args.dataset_name, data_args.dataset_config_name, cache_dir=model_args.cache_dir)                                                                                                                                                           File "/home/dshirron/.local/lib/python3.8/site-packages/datasets/load.py", line 843, in load_dataset                                                                                                                                                                         
    builder_instance.download_and_prepare(                                                                                                                                                                                                                                     
  File "/home/dshirron/.local/lib/python3.8/site-packages/datasets/builder.py", line 608, in download_and_prepare                                                                                                                                                              
    self._download_and_prepare(                                                                                                                                                                                                                                                
  File "/home/dshirron/.local/lib/python3.8/site-packages/datasets/builder.py", line 698, in _download_and_prepare                                                                                                                                                                 verify_splits(self.info.splits, split_dict)                                                                                                                                                                                                                                  File "/home/dshirron/.local/lib/python3.8/site-packages/datasets/utils/info_utils.py", line 74, in verify_splits                                                                                                                                                             
    raise NonMatchingSplitsSizesError(str(bad_splits))                                                                                                                                                                                                                         
datasets.utils.info_utils.NonMatchingSplitsSizesError: [{'expected': SplitInfo(name='validation', num_bytes=38165657946, num_examples=13799838, dataset_name='c4'), 'recorded': SplitInfo(name='validation', num_bytes=37875873, num_examples=13863, dataset_name='c4')}] 

## Environment info
- `datasets` version: 1.10.2
- Platform: Linux-5.4.0-58-generic-x86_64-with-glibc2.29
- Python version: 3.8.10
- PyArrow version: 4.0.1
Error loading C4 realnewslike dataset 
 ## Describe the bug
Error loading C4 realnewslike dataset. Validation part mismatch

## Steps to reproduce the bug
```python
 raw_datasets = load_dataset('c4', 'realnewslike', cache_dir=model_args.cache_dir)
## Expected results
success on data loading
## Actual results
Downloading: 100%|████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████| 15.3M/15.3M [00:00<00:00, 28.1MB/s]Traceback (most recent call last):                                                                                                                                                                                                                                             
  File "run_mlm_tf.py", line 794, in <module>                                                                                                                                                                                                                                  
    main()                                                                                                                                                                                                                                                                     
  File "run_mlm_tf.py", line 425, in main                                                                                                                                                                                                                                      
    raw_datasets = load_dataset(data_args.dataset_name, data_args.dataset_config_name, cache_dir=model_args.cache_dir)                                                                                                                                                           File "/home/dshirron/.local/lib/python3.8/site-packages/datasets/load.py", line 843, in load_dataset                                                                                                                                                                         
    builder_instance.download_and_prepare(                                                                                                                                                                                                                                     
  File "/home/dshirron/.local/lib/python3.8/site-packages/datasets/builder.py", line 608, in download_and_prepare                                                                                                                                                              
    self._download_and_prepare(                                                                                                                                                                                                                                                
  File "/home/dshirron/.local/lib/python3.8/site-packages/datasets/builder.py", line 698, in _download_and_prepare                                                                                                                                                                 verify_splits(self.info.splits, split_dict)                                                                                                                                                                                                                                  File "/home/dshirron/.local/lib/python3.8/site-packages/datasets/utils/info_utils.py", line 74, in verify_splits                                                                                                                                                             
    raise NonMatchingSplitsSizesError(str(bad_splits))                                                                                                                                                                                                                         
datasets.utils.info_utils.NonMatchingSplitsSizesError: [{'expected': SplitInfo(name='validation', num_bytes=38165657946, num_examples=13799838, dataset_name='c4'), 'recorded': SplitInfo(name='validation', num_bytes=37875873, num_examples=13863, dataset_name='c4')}] 

## Environment info
- `datasets` version: 1.10.2
- Platform: Linux-5.4.0-58-generic-x86_64-with-glibc2.29
- Python version: 3.8.10
- PyArrow version: 4.0.1 
 Hi @danshirron, 
`c4` was updated few days back by @lhoestq. The new configs are `['en', 'en.noclean', 'en.realnewslike', 'en.webtextlike'].` You'll need to remove any older version of this dataset you previously downloaded and then run `load_dataset` again with new configuration.