MB-7375: Return TMPFAIL for locked key when doing touch or gat

Change-Id: I7c5205a6c0a62c887e2681f98e46f056852b1ac7
Reviewed-on: http://review.couchbase.org/24281
Reviewed-by: Chiyoung Seo <chiyoung.seo@gmail.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>