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/ip-two-pools-mixed/pretest.dat

@@ -4,10 +4,10 @@ moon::ipsec pool --add intpool --start 10.4.0.1 --end 10.4.1.244 --timeout  0 2>
 moon::iptables-restore < /etc/iptables.rules
 carol::iptables-restore < /etc/iptables.rules
 alice::iptables-restore < /etc/iptables.rules
-carol::ipsec start
 moon::ipsec start
+carol::ipsec start
 alice::ipsec start
-carol::sleep 2
+carol::expect-connection home
 carol::ipsec up home
+alice::expect-connection home
 alice::ipsec up home
-alice::sleep 1