[3.14] gh-134679: Fix assertion failure in QSBR (gh-134811) (gh-134814)

This is the same underlying bug as gh-130519. The destructor may call
arbitrary code, changing the `tstate->qsbr pointer` and invalidating the
old `struct _qsbr_thread_state`.
(cherry picked from commit a4d37f88b66bc9a66b2ab277aa66a2a6b20821fa)

Co-authored-by: Sam Gross <colesbury@gmail.com>