Minor Description
The current test support code uses single thread executor instances as defense against hangs on test tearDown but is a bit aggressive with it as it also does Broker start / stop in an executor and never reuses them so every test run requires three to four threads just to start stop. There's also some thread interruption bits that blindly interrupt anything that is not the main thread which could lead to problems with the JUnit threads etc. We can reduce this all down to one executor to close the legacy QPid JMS client connection which does sometimes hang on close.
This shaves off anywhere from 1.5 to 2 minutes from the test run.