Fix HF_ENDPOINT not handled correctly

[Wauplin]

Fix #2152. Related to #2120 and to this internal slack thread.

Uploading an LFS file fails because RepoUrl(...).endpoint was not correctly overwritten with HF_ENDPOINT. We were only overwriting RepoUrl(...).endpoint but not the inner value str(RepoUrl(...)). This PR definitely fixes this by replacing it before parsing the string value. cc @padeoe.

---

Tips from @padeoe to reproduce the issue:

1. Add this line to /etc/hosts or `` to deactivate traffic to huggingace.co

127.0.0.1 [huggingface.co](http://huggingface.co/)

2. Run this script

import os


os.environ['HF_ENDPOINT'] = "https://hf-mirror.com"

from huggingface_hub import HfApi


api = HfApi() # optionally add your token here
repo_url = api.create_repo("tmp_test_mir", exist_ok=True)
repo_id = repo_url.repo_id
api.upload_file(repo_id=repo_id, path_or_fileobj=b"content", path_in_repo="file.txt")
api.upload_file(repo_id=repo_id, path_or_fileobj=b"content", path_in_repo="lfs.bin")

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[LysandreJik]

Ok, LGTM! Thanks @Wauplin

[Wauplin]

Thanks for the review! :)