Not enough space for branch name in pull request view (BB-8740)

Our feature branch names tend to get quite long once in a while.

We have quite a large project and we sometimes use namespaces, for example: feature/namespace/branchname.

When "namespace" gets long, all the branch names look the same. It is frustrating because we may have several different pull requests from different branches, but the branch name cannot be seen in the BitBucket UI (since it will be truncated and all branchnames have the same namespace). See the attached images.

Please add some space to the branch name view, thank you!