Silence more grades-related logging

lms/djangoapps/grades/new/subsection_grade.py

@@ -112,14 +112,14 @@ class SubsectionGrade(object):
         """
         Saves the subsection grade in a persisted model.
         """
-        self._log_event(log.info, u"create_model", student)
+        self._log_event(log.debug, u"create_model", student)
         return PersistentSubsectionGrade.create_grade(**self._persisted_model_params(student))
 
     def update_or_create_model(self, student):
         """
         Saves or updates the subsection grade in a persisted model.
         """
-        self._log_event(log.info, u"update_or_create_model", student)
+        self._log_event(log.debug, u"update_or_create_model", student)
         return PersistentSubsectionGrade.update_or_create_grade(**self._persisted_model_params(student))
 
     def _compute_block_score(