Separate or Parameterize CFEngine/DaskEngine Tests

In #2506 , we adopted a half and half strategy of parametrizing the test_automl_dask.py tests to test the CFEngine, but made a separate (but very similar) test file for the CFEngine itself. The reasoning behind this was to try and sidestep around some of the flakiness of the dask tests, but this continues to render the automl tests susceptible to dask flakiness.

This issue covers picking either the total separation of the CFEngine tests into 4 separate files, test_cf_engine.py, test_automl_cf.py, test_dask_engine.py and test_automl_dask.py, or the parametrization of the existing three test files into just a test_engine.py and test_automl_engine.py