IsolatedJMX should not release all TCPEndpoints on instance shutdown

In the original implementation of the JMX feature, we fixed some memory leaks by clearing some internal state in Java’s TCPEndpoint. However, that implementation was overly aggressive and cleared the whole map, vs. just removing the endpoints created by the individual instances. This causes issues when you remove a node from the cluster (as all of the endpoints are cleared, not just the ones in use by that instance).
 
In stead, we should check if the endpoint was created by the instance in question and only remove it if it was.