Support cluster_group in the consumer
The consumer needs to inspect the incoming events and route them to the appropriate cluster. Adjust the consumer to accept a mapping of cluster groups to elasticsearch urls, and then split the incoming invent stream to sink to the individual elasticsearch clusters.
While we don't expect to have unknown cluster groups flowing through the system, to keep an eye on that a new metric was added to count unroutable update events.
Change-Id: I6a3b0668464dab69bd21c70b41616c063d2a7ad1