[JENKINS-73280] Migrate to Jakarta EE 9

[Dohbedoh]

Started draft for Jakarta EE 9 migration.

Testing done

TBD

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests - that demonstrates feature works or fixes the issue

[Dohbedoh]

Rebased to fix the merge conflict. Should be good now.

[jglick]

Generally prefer using regular Git merge conflict resolution (from the GUI or CLI) since force-pushing makes it impossible for reviewers to check the incremental diff—have to start from scratch. Fortunately in this case the diff is fairly short.