fix(nodes): do not freeze or cache config in context wrapper

- The config is already cached by the config class's `get_config()` method.
- The config mutates itself in its `root_path` property getter. Freezing the class makes any attempt to grab a path from the config error. Unfortunately this means we cannot easily freeze the class without fiddling with the inner workings of `InvokeAIAppConfig`, which is outside the scope here.

invokeai/app/services/shared/invocation_context.py

@@ -357,24 +357,10 @@ class ModelsInterface(InvocationContextInterface):
 
 
 class ConfigInterface(InvocationContextInterface):
-    def __init__(self, services: InvocationServices, context_data: InvocationContextData) -> None:
-        super().__init__(services, context_data)
-        # Config cache, only populated at runtime if requested
-        self._frozen_config: Optional[InvokeAIAppConfig] = None
-
     def get(self) -> InvokeAIAppConfig:
-        """
-        Gets the app's config. The config is read-only; attempts to mutate it will raise an error.
-        """
+        """Gets the app's config."""
 
-        if self._frozen_config is None:
-            # The config is a live pydantic model and can be changed at runtime.
-            # We don't want nodes doing this, so we make a frozen copy.
-            self._frozen_config = self._services.configuration.get_config().model_copy(
-                update={"model_config": ConfigDict(frozen=True)}
-            )
-
-        return self._frozen_config
+        return self._services.configuration.get_config()
 
 
 class UtilInterface(InvocationContextInterface):