chore: Simplify the unchanged overrided method in VariableAggregatorNode (#14175)

api/core/workflow/nodes/variable_aggregator/variable_aggregator_node.py

-from collections.abc import Mapping, Sequence
-from typing import Any
-
 from core.workflow.entities.node_entities import NodeRunResult
 from core.workflow.nodes.base import BaseNode
 from core.workflow.nodes.enums import NodeType
                         break
 
         return NodeRunResult(status=WorkflowNodeExecutionStatus.SUCCEEDED, outputs=outputs, inputs=inputs)
-
-    @classmethod
-    def _extract_variable_selector_to_variable_mapping(
-        cls, *, graph_config: Mapping[str, Any], node_id: str, node_data: VariableAssignerNodeData
-    ) -> Mapping[str, Sequence[str]]:
-        """
-        Extract variable selector to variable mapping
-        :param graph_config: graph config
-        :param node_id: node id
-        :param node_data: node data
-        :return:
-        """
-        return {}