Source code rules - Add a way to reset branch protections (unprotect a branch)
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### Proposal
Add a button to reset the branch protection settings of a branch.
Button could have a label of one of the following subject to solution validation:
- Unprotect branch
- Remove protections
- Reset protections
- Reset
- Set as default
### Background
Related to this issue is this question from https://gitlab.com/gitlab-org/ux-research/-/issues/1993#note_1048536732
> we are missing an unprotect branch button
From this issue's description, if the user was to "unprotect" a branch they would need to revert the settings back to default and save the changes.
Prior to the Branch Rules reorganization, to unprotect a branch would mean deleting it from the list and the button to delete the branch protection was called `Unprotect`

issue