benchmark: remove misc/v8-bench.js

These v8 benchmarks are oudated and have been replaced by
Octane in the upstream. The benchmarking working group
has already been benchmarking Octane, so this file
can be removed now.

PR-URL: #16126
Ref: #16119
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

Author: joyeecheung