test: remove unused uncaughtException handler

This has been unused since cbc3ef64.

Refs: https://github.com/nodejs/node/pull/23053

PR-URL: https://github.com/nodejs/node/pull/25641


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>