Replication keeps accumulating znodes

If there is an error while creating the replication source on adding the peer, the source if not added to the in memory list of sources but the replication peer is.
However, in such a scenario, when you remove the peer, it is deleted from zookeeper successfully but for removing the in memory list of peers, we wait for the corresponding sources to get deleted (which as we said don't exist because of error creating the source).
The problem here is the ordering of operations for adding/removing source and peer.
Modifying the code to always remove queues from the underlying storage, even if there exists no sources also requires a small refactoring of TableBasedReplicationQueuesImpl to not abort on removeQueues() of an empty queue