fix and use ns_config_replica:get_compressed

Change-Id: I7db8172e035ffb0ea873b76e74cad0f0fd470eba
Reviewed-on: http://review.couchbase.org/41924
Tested-by: Artem Stemkovski <artem@couchbase.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>