Fix: Fixed the issue where the connection lines of placeholder nodes in the agent canvas could not be displayed #9869 (#10485)

### What problem does this PR solve?

Fix: Fixed the issue where the connection lines of placeholder nodes in
the agent canvas could not be displayed #9869

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

web/src/pages/agent/store.ts

@@ -39,7 +39,6 @@ export type RFState = {
   selectedEdgeIds: string[];
   clickedNodeId: string; // currently selected node
   clickedToolId: string; // currently selected tool id
-  highlightedPlaceholderEdgeId: string | null;
   onNodesChange: OnNodesChange<RAGFlowNodeType>;
   onEdgesChange: OnEdgesChange;
   onEdgeMouseEnter?: EdgeMouseHandler<Edge>;
@@ -90,7 +89,6 @@ export type RFState = {
   ) => void; // Deleting a condition of a classification operator will delete the related edge
   findAgentToolNodeById: (id: string | null) => string | undefined;
   selectNodeIds: (nodeIds: string[]) => void;
-  setHighlightedPlaceholderEdgeId: (edgeId: string | null) => void;
 };
 
 // this is our useStore hook that we can use in our components to get parts of the store and call actions
@@ -103,7 +101,6 @@ const useGraphStore = create<RFState>()(
       selectedEdgeIds: [] as string[],
       clickedNodeId: '',
       clickedToolId: '',
-      highlightedPlaceholderEdgeId: null,
       onNodesChange: (changes) => {
         set({
           nodes: applyNodeChanges(changes, get().nodes),
@@ -530,9 +527,6 @@ const useGraphStore = create<RFState>()(
           })),
         );
       },
-      setHighlightedPlaceholderEdgeId: (edgeId) => {
-        set({ highlightedPlaceholderEdgeId: edgeId });
-      },
     })),
     { name: 'graph', trace: true },
   ),