Revert "Revert "(TreeNode): remove implicit title setting""

This reverts commit fbfd6df.

Author: msmx-mnakagawa

src/scripts/TreeNode.tsx

@@ -92,7 +92,6 @@ const TreeNodeItem: FC<TreeNodeProps & { icon?: string }> = (props) => {
           icon={icon}
           iconSize='small'
           onClick={onToggle}
-          title={typeof label === 'string' ? `Expand ${label}` : undefined}
           // Prevent focus loss during loading by keeping the toggle button in the DOM with opacity set to 0.
           style={loading ? { opacity: 0, pointerEvents: 'none' } : undefined}
         />