testing: Make sure the whitelist plugin is ready before configuring it

testing/tests/ikev2/rw-whitelist/pretest.dat

@@ -4,12 +4,14 @@ dave::iptables-restore < /etc/iptables.rules
 carol::ipsec start
 dave::ipsec start
 moon::ipsec start
+moon::expect-connection rw
 moon::ipsec whitelist add alice@strongswan.org
 moon::ipsec whitelist add bob@strongswan.org
 moon::ipsec whitelist add carol@strongswan.org
 moon::ipsec whitelist enable
 moon::ipsec whitelist list
-carol::sleep 2 
+carol::expect-connection home
 carol::ipsec up home
+dave::expect-connection home
 dave::ipsec up home
 carol::sleep 1