Merge branch 'ps-external-redirect-fix-self-redirect' into 'master'

Fix external_redirect to not redirect to self

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/137934



Merged-by: Tetiana Chupryna <tchupryna@gitlab.com>
Approved-by: Hercules Merscher <hmerscher@gitlab.com>
Approved-by: Tetiana Chupryna <tchupryna@gitlab.com>
Co-authored-by: Paul Slaughter <pslaughter@gitlab.com>