Move planet mirrors away from rsync

[pnorman]

re: https://github.com/openstreetmap/operations/issues/678#issuecomment-1732558170

The intention is to keep the rsync service available for now. We will reduce the amount of historical data we store on planet.openstreetmap.org, which will limit what is available for rsync. Retiring the rsync service will be given with a lot of notice if/when we decide to do this.

planet.openstreetmap.org is moving to be redirects to the mirros to storage in a s3 bucket available over HTTPs. This will impact anyone using rsync, particularly those who want to retain previous files rather than just download a single file. These users are mainly or exclusively mirroring sites.

We should work on moving existing mirrors from rsync so they will have a full archive of all planet files, even if rsync will be available for awhile.

[Firefishy]

An absolutely crazy solution would be to run an EC2 instance which mounts the S3 bucket using mountpoint and serve that via rsyncd.

It checks the box for providing legacy rsync support, but would likely be highly inefficient.

(Mirrors would still need to update their mirroring paths)