test: fix child-process-fork-regr-gh-2847

The test would sometimes time out on some platforms. Take the initial
version of the test and instead of sending 100 handles, just send 2.
It still fails when run with the code before the change was introduced
and passes afterwards.

Remove test from parallel.status.

PR-URL: https://github.com/nodejs/node/pull/5121


Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Fixes: https://github.com/nodejs/node/issues/3635