msc_vlr_tests: don't abuse USSD-request to conclude connections

Previously the '*#100#' USSD-request was abused in order to
conclude the current subscriber connection. This makes the unit
tests depend on each other, for example, if one break something
in the GSM 09.11 implementation, a half of tests would fail.

Moreover, the further changes in the GSM 09.11 implementation
will make the results less predictable (i.e. session ID, etc.).
So let's introduce a separate unit test with simple request-
response logic, while more complex tests will be in TTCN.

Change-Id: I40b4caac3113263f5a06c861dff5e10d43c319b5
diff --git a/tests/msc_vlr/msc_vlr_test_reject_concurrency.c b/tests/msc_vlr/msc_vlr_test_reject_concurrency.c
index ea8c32c..580135a 100644
--- a/tests/msc_vlr/msc_vlr_test_reject_concurrency.c
+++ b/tests/msc_vlr/msc_vlr_test_reject_concurrency.c
@@ -313,11 +313,10 @@
 	EXPECT_CONN_COUNT(1);
 
 	BTW("The original CM Service Request can conclude");
-	btw("a USSD request is serviced");
-	dtap_expect_tx_ussd("Your extension is 46071\r");
-	expect_bssap_clear();
-	ms_sends_msg("0b3b1c15a11302010002013b300b04010f0406aa510c061b017f0100");
-	VERBOSE_ASSERT(bssap_clear_sent, == true, "%d");
+
+	/* Release connection */
+	expect_bssap_clear(RAN_GERAN_A);
+	conn_conclude_cm_service_req(g_conn, RAN_GERAN_A);
 
 	btw("all requests serviced, conn has been released");
 	bss_sends_clear_complete();