Myers algorithm for live edit diffing has been enabled since 10.6
without any reported problems, so we can safely remove the dynamic
programming approach with 10.8.

R=kimanh@chromium.org

Bug: chromium:1205288
Change-Id: I95c26c11e949b8c36a0b6abd54859b3936933e9d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3901811
Commit-Queue: Simon Zünd <szuend@chromium.org>
Reviewed-by: Kim-Anh Tran <kimanh@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83240}