[GSS](7.3.z) Allow core-size=0

Getting WFLYEE0112: The core-threads value must be greater than 0 when the queue-length is 0.
queue-length="0" core-threads="0" should be allowed to enable direct hand off
and get REJECT exceptions.

Right now direct hand off is possible setting core-threads=1 but then no REJECT exceptions are thrown.

Use case:queueSize=0, coreSize=0, maxSize=16 and have direct handoff. there will be no REJECT unless we try to submit more than maxSize tasks concurrently. if we submit more than maxSize concurrently, we expect to see REJECT.