As part of an incident review https://gitlab.com/gitlab-com/gl-infra/production-engineering/-/issues/12801, we limited the ability for creation of top-level groups via API https://gitlab.com/gitlab-org/gitlab/-/merge_requests/56360. The mechanism allows us to manage abuse risk on GitLab.com however is the default behaviour for GitLab SM instances. It is therefore default [enabled](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/config/feature_flags/ops/top_level_group_creation_enabled.yml) but manually disabled for GitLab.com. In order to remove the feature flag for longer term, we should migrate this to a configuration setting (& to also avoid confusion where an engineer may enable the FF in GitLab.com production)