Test disabling transformers containers in docs CI
Related to https://github.com/huggingface/doc-builder/pull/487 and [internal slack thread](https://huggingface.slack.com/archives/C04F8N7FQNL/p1711384899462349?thread_ts=1711041424.720769&cid=C04F8N7FQNL). There is now a `custom_container` option when building docs in CI. When set to `""` (instead of `"huggingface/transformers-doc-builder"` by default), we don't run the CI inside a container, therefore saving ~2min of download time. The plan is to test disabling the transformers container on a few "big" repo and if everything works correctly, we will stop making it the default container. More details on https://github.com/huggingface/doc-builder/pull/487.

cc @mishig25 
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_6757). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update. On slack it was mentioned that it was actually slower for `datasets`, should we close this one or am I missing something ? @lhoestq I converted to draft. Want to make some more tests and will let you know