Remove JBWS2942TestCase framework test and create Native and CXF specific tests validating empty EPR Metadata are dropped

JBWS-2942 tests that empty Metadata can be dropped when external EPRs already containing empty Metadata are read and then serialized.
CXF has been updated to ensure EPRs won't have empty Metadata written in the first place and the test using W3CEndpointReferenceBuilder can confirm it.

Given that it would be difficult for enhance CXF to have original JBWS-2942 passing and equally it could be tricky to enhance Native to have a W3CEndpointReferenceBuilder based test passing, it would be good to have the test removed from the framework and the original test moved to Native and a W3CEndpointReferenceBuilder based test added to JBossWS-CXF