Merge branch 'tchu-bump-obsolete-migration-keep-required-stop' into 'master'

Bump obsolete search migration keep milestone to 17.3

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/169297



Merged-by: Terri Chu <tchu@gitlab.com>
Approved-by: Ravi Kumar <rkumar@gitlab.com>