testing: Load kdf plugin in all scenarios that require it

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

testing/tests/ikev2/dhcp-static-mac/hosts/carol/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/dhcp-static-mac/hosts/dave/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/dhcp-static-mac/hosts/moon/etc/strongswan.conf

@@ -5,7 +5,7 @@ swanctl {
 }
 
 charon-systemd {
-  load = random nonce aes sha1 sha2 pem pkcs1 curve25519 gmp x509 curl revocation hmac vici kernel-netlink socket-default updown attr farp dhcp
+  load = random nonce aes sha1 sha2 pem pkcs1 curve25519 gmp x509 curl revocation hmac kdf vici kernel-netlink socket-default updown attr farp dhcp
 
   plugins {
     dhcp {