Task completion reporting and message acknowledgement removed from finally block

So, reports will not be sent, and message will not be acked in case of unexpected errors in conductor
(including ^-C interrupts, OS-originated kills etc). This ensures HighAvailability of the conductor, because unacked messages will be picked by other instances of Conductor.

This fixes MRN-588

Change-Id: I24e5985986da6fa014d7490bd8ebf00ecce7aed7