This CL also makes the PGO-related scripts executable.

Bug: v8:10470
Change-Id: Iedf81464ff591e641aae4f1f0aa37312875f2637
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3716482Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Auto-Submit: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81305}