Show Stage/Label with the new test failures summary page

### What feature do you want to see added?

If you use a "matrix style" pipeline where you have multiple stages for different OS types/architectures or even Java versions running the same tests the test overview page does not let you know what stage/label they where from.

e.g. the build summary shows the label of the stage (`ATH / ATH-${flavor}` before the test name)

whereas the test overview does not contain this information so I then do not know at a glance if the failure is in EKS, GKE, CNCF K8s, Azure or somewhere else.

### Upstream changes

Not sure if this worked before or not I think it did but have not validated.

https://github.com/jenkinsci/junit-plugin/pull/727

### Are you interested in contributing this feature?

_No response_

Start by reviewing the new test failures summary page and the related upstream junit-plugin PR #727. Trace how the build summary obtains stage or label information, then verify that the test overview shows the originating stage or label for each failure across matrix-style pipelines.

Written by the indexing model from the issue text.