Raise meaningful error when xmem replication is set up against es cluster

Xmem replication against elastic search cluster should be prohibited. We never explicitly checked for this at replication creation time. It used to be the case that such replication creation happens to fail and gives some really vague error message like "error connecting to pools/nodes on target", which does not show the root cause of the problem. Now that we are explicitly checking whether target cluster is es or couchbase in MB-25232, it makes sense to use the same check to explicitly check for this misconfiguration and raise an error that more to the point, e.g., target cluster is elastic search and does not support version 2 replication.

Actually in latest spock xmem replication against elastic search cluster no longer "happens to fail". This makes this explicit check even more important.