Merge branch 'tor/maintenance/mr-form-approvers-groups-dropdown' into 'master'

Migrate approvers_select GLDropdown to <select>

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/134029



Merged-by: Kushal Pandya <kushal@gitlab.com>
Approved-by: Kushal Pandya <kushal@gitlab.com>
Approved-by: Ammar Alakkad <aalakkad@gitlab.com>
Co-authored-by: Thomas Randolph <trandolph@gitlab.com>