ep_testsuite: Remove EP-ENGINE-TESTSUITE env var
ep_testsuite: Remove EP-ENGINE-TESTSUITE env var

Remove setting the environment variable 'EP-ENGINE-TESTSUITE' in
ep_testsuite_common. This was causing tests to crash when run with
code coverage, due to the memory passed to putenv() no longer being
valid once the testsuite shared object had been unloaded.

Given that there are no users of this environment variable at present,
simply remove it.

Change-Id: I978c3d9599b3bb96e400e62dd63e4e222c995b95
Reviewed-on: http://review.couchbase.org/54582
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Trond Norbye <60edd2ef23891a753f231b0c6f161dc634079a93@gmail.com>

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