[AMQ7, message expiry, auto-delete] auto-created queue may not auto-deleted when message expire

Previously, the broker did not delete an automatically-created queue in the case where no consumers ever connected to the queue and all messages on the queue had expired. This issue is resolved. The broker deletes the automatically-created queue in this situation.

1) the producer is sending messages with a on-zero TTL/Expiration set (I used 1000ms) to a queue that does not exist. 2) this triggers an auto-create 3) stop producer 4) the existing messages expire after a little while RESULT: the queue has zero messages and if a consumer never attaches, the queue is not auto-deleted. If a consumer is attached to the queue at some point and exits, the queue is auto-deleted, even if some messages expire.