testing: Load kdf plugin in all scenarios that require it

Once we use plugin-provided prf+() these won't work otherwise.

testing/tests/ikev2/rw-eap-md5-rsa/hosts/carol/etc/strongswan.conf

@@ -5,5 +5,5 @@ swanctl {
 }
 
 charon-systemd {
-  load = random nonce aes md5 sha1 sha2 pem pkcs1 curve25519 gmp x509 curl revocation hmac vici kernel-netlink socket-default eap-md5 updown
+  load = random nonce aes md5 sha1 sha2 pem pkcs1 curve25519 gmp x509 curl revocation hmac kdf vici kernel-netlink socket-default eap-md5 updown
 }

testing/tests/ikev2/rw-eap-md5-rsa/hosts/moon/etc/strongswan.conf

@@ -5,5 +5,5 @@ swanctl {
 }
 
 charon-systemd {
-  load = random nonce aes md5 sha1 sha2 pem pkcs1 curve25519 gmp x509 curl revocation hmac vici kernel-netlink socket-default eap-md5 updown
+  load = random nonce aes md5 sha1 sha2 pem pkcs1 curve25519 gmp x509 curl revocation hmac kdf vici kernel-netlink socket-default eap-md5 updown
 }