Consistent symbol names for forwarding hosts

multimap.conf and force_actions weren't using the same name

data/conf/rspamd/local.d/force_actions.conf

@@ -11,12 +11,12 @@ rules {
   }
   WHITELIST_FORWARDING_HOST_NO_REJECT {
     action = "add header";
-    expression = "WHITELIST_FORWARDING_HOST";
+    expression = "WHITELISTED_FWD_HOST";
     require_action = ["soft reject", "reject"];
   }
   WHITELIST_FORWARDING_HOST_NO_GREYLIST {
     action = "no action";
-    expression = "WHITELIST_FORWARDING_HOST";
+    expression = "WHITELISTED_FWD_HOST";
     require_action = ["greylist"];
   }
 }