test: enable setuid/setgid test

Refactor test for situations where it was expected to fail.
Move from disabled directory to parallel.

PR-URL: https://github.com/nodejs/node/pull/12403


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>