Reset VB creation flag only for vbuckets whose states are changed

Change-Id: Idf128288fe8b1413d9218f0778bd48cfb044d98f
Reviewed-on: http://review.couchbase.org/33234
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Tested-by: Chiyoung Seo <chiyoung@couchbase.com>