Archive junit xml result in job artifacts

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

We need to archive junit results in job artifacts, because an external tool need to download it when the job is finished. It will be great when it is done by jUnit function self. I now this is not big deal in groovy pipeline code, but I think it will be helpful also for others.

### Upstream changes

_No response_

Start by locating the JUnit function and the Jenkins job-artifact handling used when a job finishes. Trace how JUnit results are currently published, then determine the expected artifact location and verify that an external tool can download the archived XML after completion.

Written by the indexing model from the issue text.