ns for fx: move shadow lstm test to new API (#53828)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/53828
Moves LSTM shadow activations test to new API. In order
to enable this, adds support for passing two args instead
of one arg when copying a subgraph from A to B.
Since this was the last test of the old API, deletes
the old test case.
Test Plan:
```
python test/test_quantization.py TestFXNumericSuiteCoreAPIsModels.test_compare_shadow_activations_lstm_dynamic
```
Imported from OSS
Reviewed By: hx89
Differential Revision: D26982733
fbshipit-source-id: 03f580688dd37f3ccd688d9f444e9e79cfa84734
