MSC_Tests.ttcn: fix race condition in f_tc_proc_ss_paging_fail()

Sometimes in TC_proc_ss_paging_fail we hit a race condition. The
problem is that the paging expiration timer in OsmoMSC is set to
10 seconds by default (see MSC_PAGING_RESPONSE_TIMER_DEFAULT),
and in f_tc_proc_ss_paging_fail() we also wait 10.0 seconds.

Let's increase our timer value to 20.0 seconds,
so there will be more 10 seconds of leeway.

Change-Id: I6983e8c0cc8e1d7d1619f127e80063d71a4759d2
Related: Jenkins ttcn3-msc-test build #677
diff --git a/msc/MSC_Tests.ttcn b/msc/MSC_Tests.ttcn
index 0d54405..fbb471e 100644
--- a/msc/MSC_Tests.ttcn
+++ b/msc/MSC_Tests.ttcn
@@ -3705,8 +3705,9 @@
 		}
 	}
 
-	/* Expect GSUP PROC_SS_ERROR message */
-	f_expect_gsup_msg(gsup_rsp, T_val := 10.0);
+	/* Wait up to 20 seconds for GSUP PROC_SS_ERROR message.
+	 * OsmoMSC waits for Paging Response 10 seconds by default. */
+	f_expect_gsup_msg(gsup_rsp, T_val := 20.0);
 }
 testcase TC_proc_ss_paging_fail() runs on MTC_CT {
 	var BSC_ConnHdlr vc_conn;