🐛 Properly raise `RepoNotFoundError` when not authenticated
# What does this PR do?

Reverts #17646

If the user is not authenticated, the Hub now returns a 401 error if a repo is not found (either because it does not exist or it is private).

This PR catches that and properly raises `RepoNotFoundError` in `get_from_cache` to be consistent with the previous behaviour.

_The documentation is not available anymore as the PR was closed or merged._<|||||>> (Style changes in research_project should go in another PR normally, but why not).

Sorry, these changes were applied automatically by `make style`.
I can remove them if that's better 🙂 

<|||||>Merging since the CI failure seems unrelated