dbr quant: do not attach auto_quant_state to observers (#70256)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/70256
Somewhere in previous PRs we started attaching AutoQuantState
to observers. This PR removes this, as that has not purpose
and makes model debugging more complicated.
Test Plan:
```
python test/test_quantization.py -k DBR
```
Reviewed By: jerryzh168
Differential Revision: D33262299
Pulled By: vkuzo
fbshipit-source-id: a3543b44c517325d57f5ed03b961a8955049e682
