test: fix timeouts when running worker tests with `--worker`

These tests have been added after the original workers PR and
time out when run inside a worker by themselves.
This is needed for enabling `--worker` tests in our regular CI.

Refs: https://github.com/nodejs/build/issues/1318

PR-URL: https://github.com/nodejs/node/pull/21791


Reviewed-By: Jon Moss <me@jonathanmoss.me>
Reviewed-By: Refael Ackermann <refack@gmail.com>