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/ikev2/inactivity-timeout/evaltest.dat

@@ -5,4 +5,4 @@ carol::sleep 11::NO
 carol::cat /var/log/daemon.log::deleting CHILD_SA after 10 seconds of inactivity::YES
 moon:: ipsec status 2> /dev/null::rw.*INSTALLED::NO
 carol::ipsec status 2> /dev/null::home.*INSTALLED::NO
-carol::ping -c 1 -s 120 -p deadbeef PH_IP_ALICE::128 bytes from PH_IP_ALICE: icmp_req=1::NO
+carol::ping -c 1 -W 1 -s 120 -p deadbeef PH_IP_ALICE::128 bytes from PH_IP_ALICE: icmp_req=1::NO