* A test to verify JENKINS-44657 is working in core

* [JENKINS-44657] Move sub-job's buildsdir when outside of itemrootdir.

* [JENKINS-44657] Fix UsageStatisticsTest

Because we've added a test dependency that affects it.

* [JENKINS-44657] Normalize the path before comparing

* [JENKINS-44657] Use MockFolder instead of folders-plugin

for tests

* [JENKINS-44657] Document and annotate isDefaultBuildDir

* [JENKINS-44657] isDescendant doesn't throw IOException any more

* [JENKINS-44657] catch InvalidPathException and rethrow as IOException