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.

That file was wrongly stored as ISO-8859-1, resulting in screwed accents
in the Jenkins UI.

[JENKINS-32478] Split of test harness into separate artifact

The jline code appears to not use junit at all and this erronous dep
causes us to pull in junit and hamcrest without any good reason.

[JENKINS-19565] Pass ${it} to contents of dropdownDescriptorSelector

[JENKINS-32190] Check init status in UsageStatistics

[JENKINS-24696] WebAppMain.contextDestroyed produces weird errors