If multiple isolates are running concurrently and one of them calls
`quit`, we should not delete the counters map, because another isolate
might still access it.

R=mlippautz@chromium.org
CC=nikolaos@chromium.org

Bug: v8:12453
Change-Id: I6d41478f188f0043b7d6055b0872574c28fd3039
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3310807Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78226}