testing: Load kdf plugin in all scenarios that require it

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

testing/tests/ikev2/net2net-route/hosts/moon/etc/strongswan.conf

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

testing/tests/ikev2/net2net-route/hosts/sun/etc/strongswan.conf

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