MB-9096: killed unused ns_vbucket_mover:run_code

It was used for 1.8.x mode of rebalance.

Change-Id: Idfd2db742a6af4d272d36753b3eb706761630c1e
Reviewed-on: http://review.couchbase.org/29320
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Artem Stemkovski <artem@couchbase.com>