Integrated docker-registry will be cleaned up - images/layers without named tag will be deleted. This is planned for 2019.11.19-22. See https://gitlab.com/gitlab-org/gitlab-ce/issues/25322, https://gitlab.com/gitlab-org/omnibus-gitlab/merge_requests/3097.

Merge requests are a place to propose changes you've made to a project and discuss those changes with others

Interested parties can even contribute by pushing commits if they want to.