We had a --log-instruction-stats option which would count executed instructions,
splitting them into categories. We haven't used this for some years so we're
proposing to just remove the code so it doesn't bitrot and allows further
cleanups.

Change-Id: If24d11608823e24689ea02f09f5e93b4a5acd636
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2002819Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Pierre Langlois <pierre.langlois@arm.com>
Cr-Commit-Position: refs/heads/master@{#65826}