test: fix test-benchmark-zlib

The addition of brotli to zlib benchmarks means that test-benchmark-zlib
needs to be modified. This is that modification.

PR-URL: https://github.com/nodejs/node/pull/25365


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>