gh-126599: Refactor the _PyOptimizer APIs

[xuantengh]

Hi this is my draft to remove the _PyOptimizer_NewCounter and _PyOptimizer_NewUOpOptimizer APIs, where the related tests are removed or skipped.

For the most challenging _PyOptimizer_Optimize, I'm still trying to figure out how to achieve its functionality in generated interpreter. To remove the "artificial boundaries", should we just remove this API call and replace its code in the JUMP_BACKWARD, _EXIT_TRACE and _DYNAMIC_EXIT instruction cases?

• Issue: Remove the _PyOptimizer APIs #126599

[xuantengh]

cc @brandtbucher @rruuaanng

[rruuaanng]

For the most challenging _PyOptimizer_Optimize, I'm still trying to figure out how to achieve its functionality in generated interpreter. To remove the "artificial boundaries", should we just remove this API call and replace its code in the JUMP_BACKWARD, _EXIT_TRACE and _DYNAMIC_EXIT instruction cases?

Please do not open unfinished PR. (Alternatively, you can convert it to a draft PR.)