rabbit: restore synchronous ack/requeue

In https://review.openstack.org/#/c/436958, we fix a thread safety
issue. But we make the ack/requeue of message asynchronous. In nominal
case, it works, but if network/rabbit connection issue occurs this
can result to rpc call handle twice. By chance we double check already
processed message ids, and drop duplicates, but that if the message
goes to another node, the mitigation won't work.

This restore the previous behavior, to ensure we run application
callback of rpc.call/rpc.cast only when the message have been
successfully ack.

Change-Id: I62b9e09513e3ebfebc64a941d4b21b6c053b511d
(cherry picked from commit da02bc21)