[3.13] gh-129185: Fix PyTraceMalloc_Untrack() at Python exit (#129191) (#129217)

gh-129185: Fix PyTraceMalloc_Untrack() at Python exit (#129191)

Support calling PyTraceMalloc_Track() and PyTraceMalloc_Untrack()
during late Python finalization.

* Call _PyTraceMalloc_Fini() later in Python finalization.
* Test also PyTraceMalloc_Untrack() without the GIL
* PyTraceMalloc_Untrack() now gets the GIL.
* Test also PyTraceMalloc_Untrack() in test_tracemalloc_track_race().

(cherry picked from commit 46c7e13c055c218e18b0424efc60965e6a5fe6ea)