chore: fix flaky middleware matcher test (#49555)
```
✕ should match query path (2857 ms)
● Middleware custom matchers basePath › should match query path
expect(received).toBe(expected) // Object.is equality
Expected: "random"
Received: ""
```
https://github.com/vercel/next.js/actions/runs/4929337370/jobs/8809028722?pr=49529#step:6:201
