dbr quant: break up test class into multiple classes (#70246)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/70246
Breaks up the large `TestQuantizeDBR` test case into
1. `TestQuantizeDBRIndividualOps` for testing functionality of ops
2. `TestQuantizeDBRMultipleOps` for testing non-fusion interactions between ops
3. `TestQuantizeDBR` for everything else
We may need to refactor this more in the future, but this should
unblock things for the near future.
Test Plan:
```
python test/test_quantization.py TestQuantizeDBR
python test/test_quantization.py TestQuantizeDBRIndividualOps
python test/test_quantization.py TestQuantizeDBRMultipleOps
```
Reviewed By: jerryzh168
Differential Revision: D33255925
Pulled By: vkuzo
fbshipit-source-id: 82db1a644867e9303453cfedffed2d81d083c9cd
