Merge branch '472669-cleanup-group-level-grouping-ff' into 'master'

Remove feature flag

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/160560



Merged-by: Bala Kumar <sbalakumar@gitlab.com>
Approved-by: Samantha Ming <sming@gitlab.com>
Approved-by: Lorenz van Herwaarden <lvanherwaarden@gitlab.com>
Approved-by: Bala Kumar <sbalakumar@gitlab.com>
Reviewed-by: Lorenz van Herwaarden <lvanherwaarden@gitlab.com>
Co-authored-by: Savas Vedova <svedova@gitlab.com>