testing: Load kdf plugin in all scenarios that require it

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

testing/tests/ikev2/mobike/hosts/alice/etc/strongswan.conf

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

testing/tests/ikev2/mobike/hosts/sun/etc/strongswan.conf

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