fix(llm_node): Ignore user query when memory is disabled. (#11106)

api/core/workflow/nodes/llm/node.py

             query = None
             if self.node_data.memory:
                 query = self.node_data.memory.query_prompt_template
-            if not query and (
-                query_variable := self.graph_runtime_state.variable_pool.get(
-                    (SYSTEM_VARIABLE_NODE_ID, SystemVariableKey.QUERY)
-                )
-            ):
-                query = query_variable.text
+                if not query and (
+                    query_variable := self.graph_runtime_state.variable_pool.get(
+                        (SYSTEM_VARIABLE_NODE_ID, SystemVariableKey.QUERY)
+                    )
+                ):
+                    query = query_variable.text
 
             prompt_messages, stop = self._fetch_prompt_messages(
                 user_query=query,