Clean up units + some issues that surfaced during the cleanup (#3377)

Summary:

As titled, a bit of cleanup and ensuring that we choose the correct GS + experiment types

Reviewed By: mgarrard

Differential Revision: D69616303

ax/service/ax_client.py

@@ -1805,7 +1805,6 @@ def _gen_new_generator_run(
         # so if we just set the seed without the context manager, it can have
         # serious negative impact on the performance of the models that employ
         # stochasticity.
-
         fixed_feats = (
             InstantiationBase.make_fixed_observation_features(
                 fixed_features=fixed_features