Consumer disconnection during connection will NPE on client

If the Slow Consumer Detection plugin is applied to a queue then a newly connected consumer may be disconnected before the client as been fully informed or processed the fact that the consumer has been created.

This causes a problem as the client has some additional destination count logic that is only done after the client has fully connected.

This should be moved to before the subscription attempt is made.
There is already a comment to the same affect about adding the consumer to the _consumer map so it makes sense to move the destination counting login to the same location.