Fix Flaky test failing on prod and in master branch (#31407)

e2e-tests/playwright/lib/src/ui/pages/threads.ts

@@ -35,6 +35,7 @@ export default class ThreadsPage {
     }
 
     async toNotHaveThreadSelected() {
+        await this.noThreadSelected.waitFor({state: 'visible'});
         await expect(this.noThreadSelected).toBeVisible();
     }