[3.12] gh-119585: Fix crash involving `PyGILState_Release()` and `PyThreadState_Clear()` (GH-119753) (#119861)

Make sure that `gilstate_counter` is not zero in when calling
`PyThreadState_Clear()`. A destructor called from `PyThreadState_Clear()` may
call back into `PyGILState_Ensure()` and `PyGILState_Release()`. If
`gilstate_counter` is zero, it will try to create a new thread state before
the current active thread state is destroyed, leading to an assertion failure
or crash.
(cherry picked from commit bcc1be39cb1d04ad9fc0bd1b9193d3972835a57c)