benchmark: fix timeout in write-stream-throughput

PR-URL: https://github.com/nodejs/node/pull/17958
Fixes: https://github.com/nodejs/node/issues/17901


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>