When the artifacts server is enabled, GitLab Rails links certain files
(e.g. HTML) to the GitLab Pages server so that the file can be rendered
instead of downloaded. However, if public pipelines are not enabled for
a public project and the user never authenticated with the Pages server,
the GitLab Artifacts API would return a 403 error. This error would be
forwarded to the user, and Pages would halt further processing.

To fix this problem, when we encounter a 403 error, we attempt to
authenticate the user if no token is available.

Relates to https://gitlab.com/gitlab-org/gitlab/-/issues/25192

Changelog: fixed