refactor(s2a): Remove unused getGroupLabel helper function

- Delete getGroupLabel function that was no longer being used in the component
- Simplify group display logic by removing redundant label formatting utility
- Clean up code to improve maintainability and reduce unused function definitions

frontend/src/pages/S2AConfig.tsx

@@ -296,12 +296,6 @@ export default function S2AConfig() {
         }
     }
 
-    // 获取分组显示文字: "name #id" 或 "#id"
-    const getGroupLabel = (id: number): string => {
-        const group = availableGroups.find(g => g.id === id)
-        return group ? `${group.name} #${id}` : `#${id}`
-    }
-
     const handleAddGroupId = () => {
         const id = parseInt(newGroupId, 10)
         if (!isNaN(id) && !formGroupIds.includes(id)) {