Intermittent PASS in `/IndexedDB/back-forward-cache-open-transaction.window.html`

https://github.com/servo/servo/actions/runs/18039184287/job/51334046848
```
  ▶ OK [expected TIMEOUT] /IndexedDB/back-forward-cache-open-transaction.window.html
  └   ▶ PASS [expected TIMEOUT] BFCache support test for page with open IndexedDB transaction
```