gh-126016: Force crossinterpreter thread states to get cleaned up

[ZeroIntensity]

• Issue: Multithreaded subinterpreters can be running during finalization #126016

[bedevere-bot]

🤖 New build scheduled with the buildbot fleet by @ZeroIntensity for commit 94b6d09 🤖

If you want to schedule another build, you need to add the 🔨 test-with-buildbots label again.

[ZeroIntensity]

Closing this, because I don't think the fix is robust enough for what we need. This works for the specific case in gh-126016, but not for gh-127041. The fix for that issue will probably end up fixing this too.