[rel-3.0.0] update ns_server ref for MB-11903 and MB-11970

Change-Id: Ieef8603089da19069d2a20fe614c8bd8ca9911d0
Reviewed-on: http://review.couchbase.org/40761
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>