https://v8.dev/blog/tags/release is the new ChangeLog!

This also removes an unused file push_to_candidate.py which wasn't deleted
earlier as it's intertwined a lot in test cases. This CL also cleans that
up.

Furthermore, logic for selecting CLs for the ChangeLog (using LOG= lines)
is removed as well. Nobody has used this feature for more than 5 release
cycles.

We'll delete the ChangeLog file in a separate CL.

Bug: v8:10010
No-Try: true
Change-Id: Idee551dc0600c3df9f784cc543897e3e18517ca1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1930616Reviewed-by: Tamer Tas <tmrts@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65191}