AIX, FreeBSD: test-cluster-disconnect-handles intermittent failures

* **Version**: master
* **Platform**: AIX
* **Subsystem**: cluster

I've seen a number of failures on this test over the last little while:

https://ci.nodejs.org/job/node-test-commit-aix/2942/nodes=aix61-ppc64/console

```
not ok 127 parallel/test-cluster-disconnect-handles
  ---
  duration_ms: 60.107
  severity: fail
  stack: |-
    timeout
  ...
```