Recovery: remove unneeded waits on recovery cancellation

When cancelling recoveries, we wait for up to 10s for the source node to be notified before continuing. This is not needed in two cases:
1) The source node has been disconnected due to node shutdown (recovery is canceled as a response to cluster state processing)
2) The current thread is the one that will be notifying the source node  (happens when when of the calls from the source nodes discoveres local index is closed)

The first one is especially important as it may delay cluster state update processing with 10s.