MSC_Tests: fix TC_sgsap_expl_imsi_det_noneps

When a subscriber is detached from non eps services, it gets fully
detached from 2G, which means that the VLR is supposed to remove the
subscriber. Lets check if the subscriber is in deed no longer known by
the VLR.

Change-Id: I2ec3f548dfcf5a9b99f10214a8bfd0c6978e253b
Related: OS#3614
diff --git a/msc/MSC_Tests.ttcn b/msc/MSC_Tests.ttcn
index 3b9ea40..c7c61eb 100644
--- a/msc/MSC_Tests.ttcn
+++ b/msc/MSC_Tests.ttcn
@@ -3862,8 +3862,10 @@
 	var octetstring mme_name := f_enc_dns_hostname(mp_mme_name);
 	SGsAP.send(ts_SGsAP_IMSI_DETACH_IND(g_pars.imsi, mme_name, combined_UE_initiated));
 	SGsAP.receive(tr_SGsAP_IMSI_DETACH_ACK(g_pars.imsi));
-	f_ctrl_get_exp(IPA_CTRL, "fsm.SGs-UE.id.imsi:" & hex2str(g_pars.imsi) & ".state", "SGs-NULL");
-	/* FIXME: How to verify that VLR has removed MM context? */
+
+	if (f_ctrl_subscr_in_vlr(hex2str(g_pars.imsi))) {
+		setverdict(fail, "subscriber not removed from VLR");
+	}
 
 	f_sgsap_bssmap_screening();