Remove footers on Challenge Listings page

Remove these links on the Challenge Listings page.

<img width="1638" alt="Screen Shot 2020-10-12 at 1 56 03 PM" src="https://user-images.githubusercontent.com/47536078/95789668-cc765e00-0c92-11eb-944a-66f145ea17cf.png">

Final Submission Guidelines

Git issue link: https://github.com/topcoder-platform/community-app/issues/5093