Reduce noise in CourseOverview->Modulestore fallback (#25434)

This was originally intended as a placeholder to remind us to
optimize the data model for sequence metadata API calls (say
by adding those fields to the CourseOverview model itself).
Logging a quarter million messages a day is overkill for this
purpose, and we will be doing another pass at the performance of
this code in the coming weeks/months.

openedx/core/djangoapps/content/course_overviews/models.py

@@ -776,7 +776,6 @@ class CourseOverview(TimeStampedModel):
         """
         Returns the course from the modulestore.
         """
-        log.warning('Falling back on modulestore to get course information for %s', self.id)
         return modulestore().get_course(self.id)
 
     @property