Merge branch '409574-remove-old-migrations-before-20220824082427-15-9' into 'master'

Removes database migrations up to 15-9-stable-ee

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/139940



Merged-by: Jennifer Li <jli@gitlab.com>
Approved-by: Matt Kasa <mkasa@gitlab.com>
Approved-by: Diogo Frazão <dfrazao@gitlab.com>
Approved-by: Jon Jenkins <jjenkins@gitlab.com>
Approved-by: Jennifer Li <jli@gitlab.com>
Co-authored-by: Leonardo Rosa <ldarosa@gitlab.com>