[$50] Don't display the bucket if there are zero items

[sushilshinde]

[SathyaJayabal]

Related: display "No challenges found" message when search returns no results. See prod for expected behaviour.

[luizrrodrigues]

@topcoder-platform/topcodercompetitors @topcoder-platform/tcxcommunity this is open for pickup

Submit in 8 hours and PR to

https://github.com/topcoder-platform/community-app/tree/feature-refactor-challengelist
https://github.com/topcoder-platform/topcoder-react-lib/tree/feature-refactor-challengelist

run npm run test before PR

[crazyk07]

Contest https://www.topcoder.com/challenges/30143197 has been created for this ticket.

This is an automated message for crazyk via Topcoder X