Avoid CI runs under users' own CircleCI personal account
# What does this PR do?

Sometimes the tests will run in the CircleCI of the user and not run our tests since they don't have access to our resources. One example is on [this PR](https://github.com/huggingface/transformers/pull/20479#issuecomment-1369690668) where the "real" tests were not run.

**We can make the new job `check_circleci_user` required (too) - once this PR is merged into `main`**
_The documentation is not available anymore as the PR was closed or merged._<|||||>The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_20981). All of your documentation changes will be reflected on that endpoint.