Add generation blocking criterion to Sobol -> MBM criterion (facebook…

…#3018)

Summary:
Pull Request resolved: facebook#3018

By adding this criterion at the sobol to mbm criterion, we push the data requirement check into the GenerationStrategy layer, which makes the most sense as having data is required for the modeling layer to succeed.

Reviewed By: saitcakmak

Differential Revision: D65434205

fbshipit-source-id: 347f04d03e55509eef149fd91cc3ded0624bbc85

ax/modelbridge/generation_strategy.py

@@ -548,6 +548,7 @@ def gen_for_multiple_trials_with_multiple_models(
             a trial being suggested and  each inner list represents a generator
             run for that trial.
         """
+        self.experiment = experiment
         trial_grs = []
         pending_observations = (
             extract_pending_observations(experiment=experiment) or {}