Reload page after changing navigation preference

Closes #34968

app/assets/javascripts/experimental_flags.js

@@ -7,5 +7,8 @@ export default () => {
     Cookies.set(el.name, el.value, {
       expires: 365 * 10,
     });
+
+    document.body.scrollTop = 0;
+    window.location.reload();
   });
 };