docs(Toolbar (compat)): update "close overflow popover" docs (#6961)

Closes #6960

Author: Lukas742

packages/compat/src/components/Toolbar/Toolbar.mdx

@@ -113,8 +113,9 @@ The overflow popover can be closed programmatically by using the `overflowPopove
 const ToolbarComponent = () => {
   const overflowPopoverRef = useRef(null);
   const handlePopoverClose = () => {
-    if (overflowPopoverRef.current.isOpen()) {
-      overflowPopoverRef.current.close();
+    const overflowPopover = overflowPopoverRef.current;
+    if (overflowPopover?.open) {
+      overflowPopover.open = false;
     }
   };
   return (