ep_testsuite: Remove dead assignments
ep_testsuite: Remove dead assignments

As identified by Clang static analyzer:

File:        ep-engine/tests/ep_testsuite.cc
Location:    line 5447, column 9
Description: Value stored to 'stream_opaque' is never read

Change-Id: Ifbc7909da0724c363bc3feb09200964f2d10a22d
Reviewed-on: http://review.couchbase.org/58267
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Chiyoung Seo <fcffc23db27b19ee4ebba46695ee6b50e09216a2@couchbase.com>

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