test_dcp_producer_stream_req_dgm: Use check() instead of cb_assert
test_dcp_producer_stream_req_dgm: Use check() instead of cb_assert

The checkXX() macros print the values when the check fails; unlike cb_assert.

Change-Id: Ifd62f14162c2a29149329735dd260f756bea3755
Reviewed-on: http://review.couchbase.org/89888
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Trond Norbye <60edd2ef23891a753f231b0c6f161dc634079a93@gmail.com>

daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine