Clustering: operational data is not showing up in the in-memory map-cache on the replicas

Whatever is written in the operational MD-SAL data-store is replicated in the cluster, but our ClusteredDataTreeChangeListener is only watching the configration data-store, so we don't get notifications for mappings added from the southbound. Southbound mappings don't follow the same pattern for adding to the map-cache as the other operations.