We do change CWD in the script which breaks relative input paths
to d8 and .js files for instance.

Drive-by-fix:
- Show clear warning if `perf record` failed

Change-Id: Ib900ca6b53307e13be459beba1e96ddfc8ee9b79
No-try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3593784Reviewed-by: Victor Gomes <victorgomes@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80057}