Merge branch 'bdenkovych-issue-405021-part-2' into 'master'

Part 2: Improve SSO enforcement specs

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/117582



Merged-by: Steve Abrams <sabrams@gitlab.com>
Approved-by: Steve Abrams <sabrams@gitlab.com>
Co-authored-by: Bogdan Denkovych <bdenkovych@gitlab.com>