Revert "src: restore stdio on program exit"

This reverts commit c2c9c0c3.
It seems to be causing hangs when piping output to other processes.

PR-URL: https://github.com/nodejs/node/pull/21257


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>