Rename relative action processor registry

Update policy_preprocessor.json to use the new relative_actions_processor registry name instead of the legacy delta_actions_processor key.

policy_preprocessor.json

@@ -12,7 +12,7 @@
       "config": {}
     },
     {
-      "registry_name": "delta_actions_processor",
+      "registry_name": "relative_actions_processor",
       "config": {
         "enabled": true,
         "exclude_joints": [
@@ -111,4 +111,4 @@
       }
     }
   ]
-}
+}