MB-9679 Treat star and chain maps compatible if num_replicas=1.

Change-Id: Ifa8daa91271989fb0f81b1d5181c0412019d5574
Reviewed-on: http://review.couchbase.org/30877
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>