test,doc: correct documentation for runBenchmark()

The function only takes two arguments.

PR-URL: https://github.com/nodejs/node/pull/40683


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Voltrex <mohammadkeyvanzade94@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>