Unquarantine the branches E2E test

What does this MR do?

The test was fixed in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/28583 and has been passing consistently.

Closes https://gitlab.com/gitlab-org/quality/nightly/issues/62

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content