msc: fix conn id in 'MGCP OK' msg (as_mgcp_ack_all_mdcx)

The MDCX OK message should contain the same connection identifier as the
MDCX contained. So far we were always sending the second conn id,
regardless of which conn id was sent in the MDCX message.

Related: SYS#5130
Change-Id: If6f7f135d95c04ee0240f3fa9ba0b18ffc6fa24a
diff --git a/msc/MSC_Tests.ttcn b/msc/MSC_Tests.ttcn
index 0d95c61..0e0d6b6 100644
--- a/msc/MSC_Tests.ttcn
+++ b/msc/MSC_Tests.ttcn
@@ -5700,6 +5700,8 @@
 private altstep as_mgcp_ack_all_mdcx(CallParameters cpars) runs on BSC_ConnHdlr {
 	var MgcpCommand mgcp_cmd;
 	[] MGCP.receive(tr_MDCX) -> value mgcp_cmd {
+			var charstring conn_id;
+			f_mgcp_find_param_entry(mgcp_cmd.params, "I", conn_id);
 			var SDP_Message sdp := valueof(ts_SDP(cpars.mgw_conn_2.mgw_rtp_ip, cpars.mgw_conn_2.mgw_rtp_ip,
 								hex2str(cpars.mgcp_call_id), "42",
 								cpars.mgw_conn_2.mgw_rtp_port,
@@ -5707,7 +5709,7 @@
 								{ valueof(ts_SDP_rtpmap(cpars.rtp_payload_type,
 											cpars.rtp_sdp_format)),
 								  valueof(ts_SDP_ptime(20)) }));
-			MGCP.send(ts_MDCX_ACK(mgcp_cmd.line.trans_id, cpars.mgw_conn_2.mgcp_connection_id, sdp));
+			MGCP.send(ts_MDCX_ACK(mgcp_cmd.line.trans_id, str2hex(conn_id), sdp));
 			repeat;
 		}
 }