Merge branch '443883-remove-lazy-merge-request-committers-ff' into 'master'

Remove lazy_merge_request_committers feature flag

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/149062



Merged-by: Marc Shaw <mshaw@gitlab.com>
Approved-by: Marc Shaw <mshaw@gitlab.com>
Co-authored-by: Patrick Bajao <ebajao@gitlab.com>