test: fix flaky test-benchmark-querystring

Allow zero iterations for short benchmark in test.

PR-URL: https://github.com/nodejs/node/pull/17517


Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>