Merge branch 'jnutt/placeholder-user-validations' into 'master'

Extra placeholder user validation

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/152499



Merged-by: Bala Kumar <sbalakumar@gitlab.com>
Approved-by: Joseph Wambua <jjoshua@gitlab.com>
Approved-by: Bala Kumar <sbalakumar@gitlab.com>
Co-authored-by: James Nutt <jnutt@gitlab.com>