Prevent index creation on over_limit tables

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/174511



Merged-by: Alper Akgun <aakgun@gitlab.com>
Approved-by: Thong Kuah <tkuah@gitlab.com>
Approved-by: Alper Akgun <aakgun@gitlab.com>
Reviewed-by: Alper Akgun <aakgun@gitlab.com>
Reviewed-by: Max Orefice <morefice@gitlab.com>
Co-authored-by: Maxime Orefice <morefice@gitlab.com>