[quant][fx][be] Remove _input_output_observed from backend_config (#92589)
Summary:
This is no longer needed, we can use dtype to decide whether an observer is needed or not
Test Plan:
python test/test_quantization.py TestQuantizeFx
python test/test_quantization.py TestQuantizeFxOps
Reviewers:
Subscribers:
Tasks:
Tags:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/92589
Approved by: https://github.com/jcaip
