investigate flaky test-http-client-race-2 on SmartOS

* **Version**: v8.0.0-pre
* **Platform**: SmartOS16-64
* **Subsystem**: http

https://ci.nodejs.org/job/node-test-commit-smartos/6613/nodes=smartos16-64/console

```console
not ok 718 parallel/test-http-client-race-2
  ---
  duration_ms: 60.142
  severity: fail
  stack: |-
    timeout
```