test: fix flaky test-process-fatal-execption-tick

Use common.busyLoop() which happens to make the test robust.

PR-URL: https://github.com/nodejs/node/pull/18461


Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>