tools: fix node args passing in test runner

This fixes a regression from 53c88fa4 so that special arguments
can once again be passed to the node executable when running tests.

PR-URL: https://github.com/nodejs/node/pull/13384


Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>