[E2E] PROMOTE TO BLOCKING: add_new_branch_rule_spec.rb

What does this MR do?

Promotes the following e2e tests to the blocking bucket:

1. Create Branch Rules Overview adds a new branch rule | Testcase | Spec metrics

This MR was created based on data from reliable e2e test report: #463733 (closed)

(This MR was automatically generated by gitlab_quality-test_tooling at 2024-05-27 02:05:39 UTC)