Fix transient failures in JBWS2150TestCaseForked

We have transient failures in JBWS2150TestCaseForked, possibly because we can end up building multiple clients in the same bus and those clients might be built against different endpoints that are however published at the same address (at different time of course).
Moreover, we should really be reading the initial server config once at the beginning of the Suite and reset values after each test method execution.