Add kwarg to disable rounding separately from `use_fwd_quant` in `aqt_dot_general_test.py`.

[copybara-service[bot]]

Add kwarg to disable rounding separately from use_fwd_quant in aqt_dot_general_test.py.

The coupling of these two parameters caused a numerical failure in some tests I wrote that took quite a while to track down.

Tested equivalence to the existing tests via:

  if use_fwd_quant is not None:
    assert disable_rounding