MB-11332: Revert "MB-10778: Return item not found instead of not stored"

This reverts commit 869a66d1d08531af65169c59b640de4546974a34.

Change-Id: I3da94cc911ea32399dd1589c9cb95a2bbc9f00e2
Reviewed-on: http://review.couchbase.org/39665
Reviewed-by: Dave Rigby <daver@couchbase.com>
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Tested-by: Chiyoung Seo <chiyoung@couchbase.com>