[quant][refactor tests] Clean up test_quantization.py (#59088)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/59088
Clean up comments and organize the tests better
Test Plan:
python test/test_quantization.py
Imported from OSS
Reviewed By: jerryzh168
Differential Revision: D28750064
fbshipit-source-id: 4c36922e25e3adea3aaa8b4d9185dc28b17aa57c
