[#741] Move data dumps to `/public` folder in bucket
[#741] Move data dumps to `/public` folder in bucket

We use the `/dumps` folder for a few other dumps (e.g. NCT data), so it's
easier to organize the dumps we want to allow people to download in another
folder.

opentrials/opentrials#741

opentrials/opentrials-airflow,opentrials/opentrials-airflow