What does this MR do?

This merge request adds support for GitLab pages authentication switches implemented by @tuomoa in gitlab-pages!94 (merged).

Checklist

See Definition of done.

• Change added to CHANGELOG.md. Not applicable for Documentation changes and minor changes.
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA, if applicable
• MR targeting master branch
• MR has a green pipeline on GitLab.com

Reviewer Checklist

In addition to above, reviewer must:

• Pipeline is green on dev.gitlab.org if the change is not touching documentation or internal cookbooks

References

https://gitlab.com/gitlab-org/gitlab-ce/issues/33422

gitlab-pages!94 (merged)

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/18589

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/33422