testing: Remove nearly all sleep calls from pretest and posttest scripts

By consistently using the `expect-connection` helper we can avoid pretty
much all previously needed calls to sleep.

testing/tests/ikev2/dynamic-initiator/pretest.dat

@@ -4,10 +4,9 @@ dave::iptables-restore < /etc/iptables.rules
 carol::ipsec start
 dave::ipsec start
 moon::ipsec start
-carol::sleep 2
+carol::expect-connection moon
 carol::ipsec up moon
-carol::sleep 1
 carol::iptables -D INPUT  -i eth0 -p udp --dport 500 --sport 500 -j ACCEPT
 carol::iptables -D OUTPUT -o eth0 -p udp --dport 500 --sport 500 -j ACCEPT
+dave::expect-connection moon
 dave::ipsec up moon
-dave::sleep 2