test: shorten test-benchmark-http

Add `--set key=""` to cut down the time it takes to run
test-benchmark-http by about a third.

Alphabetize options in `--set` list.

PR-URL: https://github.com/nodejs/node/pull/13109


Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>