[quant][graphmode] `prepare_script` takes original qconfig_dict (#35335)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/35335
We'll script the qconfig_dict in `prepare_script`
Test Plan:
regression tests in `python test/test_jit.py`
Imported from OSS
Differential Revision: D20655311
fbshipit-source-id: 002bfd905ff9a9b298a8073d42e12cfffcd1eb71
