MB-11235 duplicate "UPR>replication>remaining items" in the summary

... category for usability. I called it "UPR replication backlog"
since no particular name for it was specified in the ticket

Change-Id: I77fd9ef1bf1ae5f2ad32f9a39e3782aafb9b0c92
Reviewed-on: http://review.couchbase.org/38833
Tested-by: Artem Stemkovski <artem@couchbase.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>