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/tnc/tnccs-20-fail-resp/pretest.dat

@@ -3,6 +3,6 @@ carol::iptables-restore < /etc/iptables.rules
 moon::cat /etc/tnc_config
 carol::cat /etc/tnc_config
 moon::ipsec start
-carol::ipsec start 
-carol::sleep 1
+carol::ipsec start
+carol::expect-connection home
 carol::ipsec up home