QPID-6020: HA logging improvements - log prefix with status and ID.

Fix log prefix for RemoteBackup and PrimaryTxObserver objects.
Use short UUIDs for showing UUID sets in logs.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1619581 13f79535-47bb-0310-9956-ffa450edef68