When the debugger is active and a Promise begins executing,
Isolate::PushPromise adds a global handle for that Promise. If the
debugger is no longer attached when the Promise finishes executing, then
there is no corresponding call to PopPromise which would clean up the
global handle. To avoid leaking memory in that case, we should clean up
the Promise stack when detaching the debugger.

Bug: v8:12613
Change-Id: I47a2c37713b43b482e23e2457e96fba5f52623f4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3448949Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#79017}