[quant][graph] Update dynamic quant tests to use new qconfig (#35451)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/35451
default_dynamic_qconfig now holds activation observer
Test Plan:
python test/test_quantize_script.py
Imported from OSS
Differential Revision: D20664585
fbshipit-source-id: 78cb6747705d230d2bbcfdae59210b4b998d0d15
