ISPN-4582 JpaStoreTest random failures

* Set threadCount to 1 in surefire plugin
ISPN-4638 Add ability to remove filter/converter factories

* Extension manager service should allow for filter/converter factories
to be removed when their undeployed (via their service stop() method).
* Extension manager service should allow for Hot Rod servers to be
removed when their removed (via their service stop() method).