mgcp_client_test: also verify received conn_id

Include the parsed conn_id in the response cb printout to verify them in
mgcp_client_test.ok.

Change-Id: I6b9b18d4d0867febd75a4d29f8a2fcdf0553ae4c
diff --git a/tests/mgcp_client/mgcp_client_test.ok b/tests/mgcp_client/mgcp_client_test.ok
index 4b1e78c..5e14219 100644
--- a/tests/mgcp_client/mgcp_client_test.ok
+++ b/tests/mgcp_client/mgcp_client_test.ok
@@ -27,6 +27,7 @@
 response cb received:
   head.response_code = 200
   head.trans_id = 1
+  head.conn_id = 1
   head.comment = OK
   audio_port = 16002
   audio_ip = 10.9.1.120