Remove references to torchao's AffineQuantizedTensor (#13405)
**Summary:** TorchAO recently deprecated AffineQuantizedTensor
and related classes (https://github.com/pytorch/ao/issues/2752).
These will be removed in the next release. We should remove
references of these classes in diffusers before then.
**Test Plan:**
python -m pytest -s -v tests/quantization/torchao/test_torchao.py
Co-authored-by: Sayak Paul <spsayakpaul@gmail.com>
