Mark CI tests as xfail when 502 error
{'login': 'albertvillanova', 'id': 8515462, 'node_id': 'MDQ6VXNlcjg1MTU0NjI=', 'avatar_url': 'https://avatars.githubusercontent.com/u/8515462?v=4', 'gravatar_id': '', 'url': 'https://api.github.com/users/albertvillanova', 'html_url': 'https://github.com/albertvillanova', 'followers_url': 'https://api.github.com/users/albertvillanova/followers', 'following_url': 'https://api.github.com/users/albertvillanova/following{/other_user}', 'gists_url': 'https://api.github.com/users/albertvillanova/gists{/gist_id}', 'starred_url': 'https://api.github.com/users/albertvillanova/starred{/owner}{/repo}', 'subscriptions_url': 'https://api.github.com/users/albertvillanova/subscriptions', 'organizations_url': 'https://api.github.com/users/albertvillanova/orgs', 'repos_url': 'https://api.github.com/users/albertvillanova/repos', 'events_url': 'https://api.github.com/users/albertvillanova/events{/privacy}', 'received_events_url': 'https://api.github.com/users/albertvillanova/received_events', 'type': 'User', 'site_admin': False}
[]
[]
_The documentation is not available anymore as the PR was closed or merged._
To make CI more robust, we could mark as xfail when the Hub raises a 502 error (besides 500 error):

- FAILED tests/test_upstream_hub.py::TestPushToHub::test_push_dataset_to_hub_skip_identical_files
  - https://github.com/huggingface/datasets/actions/runs/3174626525/jobs/5171672431
  ```
  >           raise HTTPError(http_error_msg, response=self)
  E           requests.exceptions.HTTPError: 502 Server Error: Bad Gateway for url: https://hub-ci.huggingface.co/datasets/__DUMMY_TRANSFORMERS_USER__/test-16648055339047.git/info/lfs/objects/batch
  ```

- FAILED tests/test_upstream_hub.py::TestPushToHub::test_push_dataset_dict_to_hub_overwrite_files
  - https://github.com/huggingface/datasets/actions/runs/3145587033/jobs/5113074889
  ```
  >           raise HTTPError(http_error_msg, response=self)
  E           requests.exceptions.HTTPError: 502 Server Error: Bad Gateway for url: https://hub-ci.huggingface.co/datasets/__DUMMY_TRANSFORMERS_USER__/test-16643866807322.git/info/lfs/objects/verify
  ```

Currently, we mark as xfail when 500 error:
- #4845
{'url': 'https://api.github.com/repos/huggingface/datasets/issues/5058/reactions', 'total_count': 0, '+1': 0, '-1': 0, 'laugh': 0, 'hooray': 0, 'confused': 0, 'heart': 0, 'rocket': 0, 'eyes': 0}
{'url': 'https://api.github.com/repos/huggingface/datasets/pulls/5058', 'html_url': 'https://github.com/huggingface/datasets/pull/5058', 'diff_url': 'https://github.com/huggingface/datasets/pull/5058.diff', 'patch_url': 'https://github.com/huggingface/datasets/pull/5058.patch', 'merged_at': '2022-10-04T10:01:23Z'}