bsc: f_TC_cm_serv_rej: tweak f_sleep()ing

Make the test more stable by sleeping a bit before stopping all
components. Also reduce the f_sleep(3.0), an accidental leftover from
initial debugging.

Related: SYS#4878
Change-Id: I005af13baac4bca2a431b09b2a6bbfe7077342e0
diff --git a/bsc/BSC_Tests.ttcn b/bsc/BSC_Tests.ttcn
index 4fdd059..229f8d6 100644
--- a/bsc/BSC_Tests.ttcn
+++ b/bsc/BSC_Tests.ttcn
@@ -10386,7 +10386,7 @@
 {
 	f_create_chan_and_exp();
 	BSSAP.send(ts_PDU_DTAP_MT(ts_CM_SERV_REJ('02'O), '00'O));
-	f_sleep(3.0);
+	f_sleep(1.0);
 }
 testcase TC_cm_serv_rej() runs on test_CT {
 	var TestHdlrParams pars := f_gen_test_hdlr_pars();
@@ -10404,6 +10404,7 @@
 	f_ctrs_bts_add(0, "cm_serv_rej:imsi_unknown_in_hlr", 1);
 	f_ctrs_bts_verify();
 
+	f_sleep(1.0);
 	f_shutdown_helper();
 }