[FIXED JENKINS-32328] process multiple update-centers for ToolInstallers

As part of the process of getting a [new plugin parent POM](https://github.com/jenkinsci/plugin-pom) decouple from the core project
the plugin module is removed.

BuildTriggerTest.downstreamProjectShouldObserveCompletedParent failure

[FIX JENKINS-31753] Fields are aligned at the bottom

[JENKINS-26466] Decouple Node from NodeMonitor

Another fix for the future node_monitors package extraction.

This time, a simple import removal.

Downgrade “termination trace” warnings

Added missing translations for Polish language

[JENKINS-22767] Make sure only one thread actually loads a given build

[FIXED JENKINS-32478] Use released version of test harness

Transcoding from iso-8859-1 to utf-8

4 spaces missing

Junit was being pulled in transitively from jline - and was not needed by jline.
Fixed by upgrading to the version of jline that groovy uses which has fixed dependencies.