testing: enforce xauth-eap in ikev1/xauth-rsa-eap-md5-radius

As eap-radius now provides its own XAuth backend and eap-radius is loaded before
xauth-eap, we have to enforce the exact XAuth backend to use.

testing/tests/ikev1/xauth-rsa-eap-md5-radius/hosts/moon/etc/ipsec.conf

@@ -18,5 +18,5 @@ conn rw
 	leftfirewall=yes
 	right=%any
 	rightauth=pubkey
-	rightauth2=xauth
+	rightauth2=xauth-eap
 	auto=add