ggsn_tests: f_wait_icmp4: don't shutdown on error

Use setverdict(fail, …) instead of shutting down the test. Otherwise we
don't close the PDP context. This fixes TC_pdp6_act_deact failing if it
runs after a failed TC_pdp4_act_update_teid.

Change-Id: Ib31481e79fc81983ae0c36f0512c6b7dba3f28a8
diff --git a/ggsn_tests/GGSN_Tests.ttcn b/ggsn_tests/GGSN_Tests.ttcn
index 32d4a1d..6a61177 100644
--- a/ggsn_tests/GGSN_Tests.ttcn
+++ b/ggsn_tests/GGSN_Tests.ttcn
@@ -1171,8 +1171,7 @@
 				}
 			}
 			[] GTPU.receive(tr_GTPU_GPDU(g_peer_u, ?)) -> value ud {
-				Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail,
-							"Received wrong local TEID");
+				setverdict(fail, "Received wrong local TEID");
 			}
 			[] GTPU.receive { setverdict(fail); }
 			[] T_default.timeout { setverdict(fail); }