Now that code entries outlive our CodeMap, it's safe to avoid storing
CodeMap metadata after the last active profiler stops. This simplifies
lifecycle logic, and avoids retaining stale data.

Bug: v8:11054
Change-Id: If30fc0835e2033b5bcca204565e05a5cba7823ea
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3000526
Commit-Queue: Andrew Comminos <acomminos@fb.com>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75689}