MB-10240: Check vbucket existence in ItemResidentCallback
MB-10240: Check vbucket existence in ItemResidentCallback

We need to make sure the vbucket exists before trying to lookup
and item in the cache.

Change-Id: I721b6333fa59d70688facf762ef35d2d78f7fd36
Reviewed-on: http://review.couchbase.org/34386
Reviewed-by: Chiyoung Seo <fcffc23db27b19ee4ebba46695ee6b50e09216a2@couchbase.com>
Reviewed-by: Sundararaman Sridharan <52fd5d4a6dc39f24404c4ccfbc872fa0f3bb41e2@gmail.com>
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>

daverigby/kv_engine,owendCB/ep-engine,jimwwalker/ep-engine,daverigby/ep-engine,sriganes/ep-engine,daverigby/ep-engine,jimwwalker/ep-engine,sriganes/ep-engine,membase/ep-engine,owendCB/ep-engine,owendCB/ep-engine,jimwwalker/ep-engine,hisundar/ep-engine,jimwwalker/ep-engine,daverigby/kv_engine,teligent-ru/ep-engine,couchbase/ep-engine,daverigby/kv_engine,owendCB/ep-engine,daverigby/kv_engine,daverigby/ep-engine,membase/ep-engine,couchbase/ep-engine,sriganes/ep-engine,hisundar/ep-engine,hisundar/ep-engine,teligent-ru/ep-engine,teligent-ru/ep-engine,teligent-ru/ep-engine,daverigby/ep-engine,couchbase/ep-engine,couchbase/ep-engine,sriganes/ep-engine,hisundar/ep-engine,membase/ep-engine,membase/ep-engine