fix: best_model_for_estimator returns inconsistent feature_importances_ compared to automl.model (#1429)

* mrl-issue1422-0513

* fix version dependency

* fix datasets version

* test completion

---------

Co-authored-by: Runlin Mu (FESCO Adecco Human Resources) <v-runlinmu@microsoft.com>
Co-authored-by: Li Jiang <bnujli@gmail.com>

flaml/automl/automl.py

@@ -424,6 +424,8 @@ class AutoML(BaseEstimator):
             If `model_history` was set to True, then the returned model is trained.
         """
         state = self._search_states.get(estimator_name)
+        if state and estimator_name == self._best_estimator:
+            return self.model
         return state and getattr(state, "trained_estimator", None)
 
     @property