[EJBCLIENT-120] Hang in AbstractHandleableCloseable.close() when using @Clustered

Extract the logic from cluster context outside EJBClientContext for
uncoupling the operations between EJBClientContext and
ClusterContext. This removes the deadlock when both types
of operations are being invoked through the EJBClientContext.
BZ 6.x https://bugzilla.redhat.com/show_bug.cgi?id=1133980
Ah I understand.  In that case though, maybe it's better to create a lock object to use instead.  Generally I prefer synchronized blocks rather than the synchronized modifier anyway.

In other words, you don't have to extract an entire other class to have distinct synch locks.  In fact it's rather confusing.  Because the code moved, it's very difficult to determine what the functional differences from the previous revision are.