harmony-locale is shipped in m74 and m74 is already out.
Remove harmony-locale flag from the code.

Bug: v8:8910
Change-Id: If9634b6767cfe449cfa03980bbad26ceb7408c79
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1592465
Commit-Queue: Frank Tang <ftang@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61429}