Deprecate Challenge DF: first in a PR, merge to main after Nov 30

[trentmc]

This is the df-web side of EPIC "wind down Challenge DF" df-private#63.

Do it in a branch for now. Then merge to main the day when Challenge DF ends. (Approx Nov 30, but we have to time it right with the different moving parts.)

[trentmc]

Reminder: please deprecate Challenge DF from webapp.

[KatunaNorbert]

Should we remove the entire Challenge-DF page or just the substream? Users might still want to check the winners from the last round so It makes sense to keep it for at least 1 week, but after that we could just remove it

[trentmc]

Users might still want to check the winners from the last round so It makes sense to keep it for at least 1 week, but after that we could just remove it

Good point. So let's keep it as-is for this week, and then next week wholly remove the page.

[KatunaNorbert]

Good. I will remove the substream and do some small tweaks to Challenge-DF page so it points out that round 66 was the last one. Will provide an screenshot soon.

[KatunaNorbert]