testing: make curve25519 the default DH group

testing/tests/ikev2/rw-eap-sim-only-radius/pretest.dat

@@ -1,3 +1,6 @@
+moon::rm /etc/ipsec.d/cacerts/*
+carol::rm /etc/ipsec.d/cacerts/*
+dave::rm /etc/ipsec.d/cacerts/*
 moon::iptables-restore < /etc/iptables.rules
 carol::iptables-restore < /etc/iptables.rules
 dave::iptables-restore < /etc/iptables.rules