Set max page size for get courses

LEARNER-5566

lms/djangoapps/course_api/views.py

@@ -234,6 +234,7 @@ class CourseListView(DeveloperErrorViewMixin, ListAPIView):
     pagination_class = NamespacedPageNumberPagination
     serializer_class = CourseSerializer
     throttle_classes = CourseListUserThrottle,
+    max_page_size = 100
 
     # Return all the results, 10K is the maximum allowed value for ElasticSearch.
     # We should use 0 after upgrading to 1.1+: