Remove or update Day 1 / Day 2 feedback links in Big Data Mini Course

[JoshRosen]

The Big Data Mini Course, updated from the AMP Camp 3 materials, still contains links to the day 1 / day 2 feedback pages. We should update or remove these feedback links, since the two-day split is probably confusing to online viewers, and some of the questions are only relevant to in-person attendees (like the part about asking us to keep their cluster running).