test: remove setTimeout in test-net-connect-unref

Removes the setTimeout since if the test were to fail it would time out
due to the tools/test.py wrapper

PR-URL: https://github.com/nodejs/node/pull/21969


Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Jon Moss <me@jonathanmoss.me>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>