Intermittent PASS in `/websockets/back-forward-cache-with-closed-websocket-connection.window.html`

https://github.com/servo/servo/actions/runs/18049090628/job/51367419190

```
  ▶ OK [expected TIMEOUT] /websockets/back-forward-cache-with-closed-websocket-connection.window.html
  └   ▶ PASS [expected TIMEOUT] Testing BFCache support for page with closed WebSocket connection.
```