MB-15697: Expect appropriate return code based on item pager
MB-15697: Expect appropriate return code based on item pager

In the test scenario expect SUCCESS for store op only if
item pager has run. This fixes sporadic test failure in
unit test: test_memory_limit.

Change-Id: I15bd52826bbd57e54d69c82630e9bc1986e9570b
Reviewed-on: http://review.couchbase.org/55414
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Chiyoung Seo <fcffc23db27b19ee4ebba46695ee6b50e09216a2@couchbase.com>

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