[Jobs] Use current or stored token in a Job secrets (#3272)
* hf_auth in jobs secrets
* --secrets HF_TOKEN
* also in --env for consistency
* factorize
* mypy
* Apply suggestions from code review
Co-authored-by: Lucain <lucain@huggingface.co>
* style
* update regex
* add test
* Update src/huggingface_hub/utils/_dotenv.py
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Co-authored-by: Lucain <lucain@huggingface.co>