test flake: TestWatchdog_Timeout

Seen here: https://github.com/coder/coder/actions/runs/7801997439/job/21278471914

```
=== Failed
=== FAIL: coderd/database/pubsub TestWatchdog_Timeout (10.00s)
    t.go:99: 2024-02-06 15:26:26.334 [debu]  context done; exiting publishLoop
    t.go:99: 2024-02-06 15:26:26.334 [debu]  context done; exiting subscribeMonitor
    watchdog_test.go:85: timeout
```