Show MR link for branch based pipelines

Release notes

You may easily want to access branch details from a merge request. Previously, this was a difficult action for you to do. Now, there is a link to the merge request details for branch-based pipelines to simplify developer workflows.

Problem to solve

Issue created from #414756

During the pipeline details header redesign we unintentionally made changes to logic to exclude basic/branch-based pipelines.

Related thread with more context #414756 (comment 1442436964)

We need to re-introduce the ability for branch pipeline users to have quick access to related MRs inside the pipeline details header.

User experience goal

Quick access to related MRs

Proposal

Refactor the ref_text method in app/presenters/ci/pipeline_presenter.rb to include the MR link if present for branch pipelines.

I.E edit the strings For %{link_to_pipeline_ref} and For %{ref} to include a MR link.

It will be helpful to look at the old code that used to display all related MRs. But now we will just display one MR (the most relevant MR).

On the UI

When only 1 related MR present

Related merge requests !23433 to merge branch xyz into master

When more than 1 MR

3 related merge requests: !123, !456, !111.

What does success look like, and how can we measure that?

Branch pipeline users see related MRs and have quick access to the MR link

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