[release] Deprecate v8rel

NOTRY=true

Change-Id: Ie97090587841830ed82097f5411131a9dc9ff5e6
Reviewed-on: https://chromium-review.googlesource.com/1009742
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Michael Hablich <hablich@chromium.org>
Reviewed-by: Sergiy Byelozyorov <sergiyb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52563}