Bring back the branch of the MR in the main view
### Problem When reviewing you often end up checking out the branch yourself locally, and need to find what branch the MR is associated with. The new layout hides this data, and it's hard to find. ### Actionable insight - https://gitlab.com/gitlab-org/gitlab/-/issues/233271 - https://gitlab.com/gitlab-org/gitlab/-/issues/290641 <!-- triage-serverless v3 PLEASE DO NOT REMOVE THIS SECTION --> *This page may contain information related to upcoming products, features and functionality. It is important to note that the information presented is for informational purposes only, so please do not rely on the information for purchasing or planning purposes. Just like with all projects, the items mentioned on the page are subject to change or delay, and the development, release, and timing of any products, features, or functionality remain at the sole discretion of GitLab Inc.* <!-- triage-serverless v3 PLEASE DO NOT REMOVE THIS SECTION -->
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