Disable create-on-push feature for user/group
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### Problem to solve
Create-on-push has resulted in a number of implicit project creations on my behalf that I've needed to delete. I find the feature less than helpful, personally, because such projects are not linked as forks and then require deleting the generated project by hand.
### Intended users
Those who do not want implicit project creation.
### Further details
Users won't be confused why their "fork" is not a fork on GitLab.
### Proposal
Offer an option to disable implicit project creation for users and groups.
### Permissions and Security
The user themselves or the group owners.
### Documentation
Notes on the option and possibly screenshots.
### What does success look like, and how can we measure that?
A way to disable implicit project creation exists.
### Links / references
gitlab-ce#26388
issue