testing: Avoid delays with ping by using -W and -i options

With -W we reduce timeouts when we don't expect a response.  With -i the
interval between pings is reduced (mostly in case of auto=route where
the first ping yields no reply).

testing/tests/tnc/tnccs-20-block/evaltest.dat

@@ -9,4 +9,4 @@ moon:: cat /var/log/daemon.log::added group membership 'allow'::YES
 moon:: cat /var/log/daemon.log::authentication of 'carol@strongswan.org' with EAP successful::YES
 moon:: cat /var/log/daemon.log::EAP method EAP_TTLS failed for peer dave@strongswan.org::YES
 carol::ping -c 1 PH_IP_ALICE::64 bytes from PH_IP_ALICE: icmp_req=1::YES
-dave:: ping -c 1 PH_IP_ALICE::64 bytes from PH_IP_VENUS: icmp_req=1::NO
+dave:: ping -c 1 -W 1 PH_IP_ALICE::64 bytes from PH_IP_VENUS: icmp_req=1::NO