* Contributes to https://gitlab.com/gitlab-org/gitlab/-/issues/351520
* Sentry error:
https://sentry.gitlab.net/gitlab/gitlabcom/issues/3091321

**Problem**

Merge request rebase action does not verify whether the source branch
is protected from the force push.

**Solution**

* Verify if the branch permits force push
* Show notification when the user tries to rebase this branch

Changelog: fixed