Create Branch Rule mutation to delete approval settings
<!--IssueSummary start-->
<details>
<summary>
Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards.
</summary>
- [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=520017)
</details>
<!--IssueSummary end-->
Part of https://gitlab.com/gitlab-org/gitlab/-/issues/503805+
We need to create a mutation for handling updating approval settings for a branch rule
This should only be allowed for non-wildcard protected branches. All branches and All protected branches are not supported
issue