Submission count does not include checkpoint submissions

Submission count mismatch for design contests between v4 and v5

example https://beta-community-app.topcoder.com/challenges/208e6774-8263-4c3a-a77f-afe4c84a888f https://www.topcoder.com/challenges/30132044

<img width="1440" alt="Screenshot 2020-07-24 at 10 48 49 AM" src="https://user-images.githubusercontent.com/58783823/88362948-ef802880-cd9b-11ea-92e3-321e4899cf6d.png">

cc @lakshmiathreya

Final Submission Guidelines

Git issue link: https://github.com/topcoder-platform/community-app/issues/4681