[quant][be] Clean up QAT tests in test_quantize_pt2e.py (#107991)
Summary: This commit does 4 main things:
1. When verifying QAT numerics, automatically check both the
per tensor and the per channel cases, and automatically verify
convert numerics
2. When verifying the QAT graph, automatically check both the
per tensor and the per channel cases
3. Merge verify graph and verify numerics tests for conv-bn
4. Fix `test_prepare_qat_conv_bn_fusion_getitem_placeholder`,
which was no longer testing the right thing recent capture
changes, since the maxpool op is no longer followed by a
getitem node. However, we do still need this test for other
ops that *are* followed by getitem nodes (e.g. standalone BN).
Items (1) - (3) make the QAT tests significantly less verbose
and easier to read.
Test Plan:
python test/test_quantization.py TestQuantizePT2E
python test/test_quantization.py TestQuantizePT2EModels
Reviewers: jerryzh168, kimishpatel
Subscribers: jerryzh168, kimishpatel, supriyar
Pull Request resolved: https://github.com/pytorch/pytorch/pull/107991
Approved by: https://github.com/jerryzh168
