MB-7173: disable index replica if data replication is disabled

Change-Id: I53d230d1e7aa861056f3f6ddf376390892887044
Reviewed-on: http://review.couchbase.org/35678
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>