[tools] Clean up py2 code

Bug: chromium:1292013
Change-Id: Ic2c3a197005a2136bb0eda4cbb36d8eb57f42a7c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3523047


Reviewed-by: Liviu Rau <liviurau@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79507}