Add CVS container registry toggle behind FF

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/147968



Merged-by: David Pisek <dpisek@gitlab.com>
Approved-by: Russell Dickenson <rdickenson@gitlab.com>
Approved-by: Daniel Tian <dtian@gitlab.com>
Approved-by: David Pisek <dpisek@gitlab.com>
Reviewed-by: Thiago Figueiró <tfigueiro@gitlab.com>
Reviewed-by: David Pisek <dpisek@gitlab.com>
Co-authored-by: Fernando Cardenas <fcardenas@gitlab.com>