[dynamo] Minor fixes and clean-up in eval_frame.c (#100496)
This fixes a few reference counting bugs in eval_frame.c, simplifies a few functions a bit, and adds a few missing error handling code paths. Probably the only important reference counting bug is that `call_callback` previously leaked `THPPyInterpreterFrame` in Python 3.11+.
Summary below:
- eval_frame_callback_get shouldn't incref Py_None
- Don't leak THPPyInterpreterFrame in Python 3.11+
- set_profiler_hooks would decref profiler_start_hook and profiler_end_hook too many times if called with None as an argument (but we never actually used that code path).
- Simplify some argument parsing
- Only create guard_profiler_name_str once
- Add a few missing error checks
Pull Request resolved: https://github.com/pytorch/pytorch/pull/100496
Approved by: https://github.com/albanD
