MB-9608 remove ns_config_ets_dup. move its functionality to

.. ns_config. this eliminates some messaging and makes the
whole thing less raceful

Change-Id: I9173beaa010a01378ee2e031f4d5d2233a39f7cf
Reviewed-on: http://review.couchbase.org/30436
Tested-by: Artem Stemkovski <artem@couchbase.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>