"Restricted visibility levels" that cannot even be overridden by admins

Problem to solve

I would like to have a setting globally to a GitLab instance to prevent that even an admin can accidentally create a public repo.

Intended users

Gitlab admins

Further details

Benefit is to prevent accidential disclosure of confidential information by having someone -- even an admin -- create a public repo.

Proposal

Implement a setting that can be put in the initial config to set up GitLab. Overriding that setting should not be possible from the GUI or API.