Remove debug print statements from launchertest.MainLauncherTest

The launchertest.MainLauncherTest unit test prints several debug statements to the console of the form:

class init: thread = Thread[JavaFX Application Thread,5,main]
main: thread = Thread[main,5,main]
constructor: thread = Thread[JavaFX Application Thread,5,main]
init: thread = Thread[JavaFX-Launcher,5,main]
start: thread = Thread[JavaFX Application Thread,5,main]
stop: thread = Thread[JavaFX Application Thread,5,main]
...

These should be removed.