make rclone work like rsync --archive --delete-after or s3cmd --delete-removed --delete-after

The support for rsync and s3cmd do a full sync including removing remote files that are not present locally. The rclone support should behave the same way. This shows itself as a bug in the rclone wrapper function when switching an existing repo to index_only: true. All of the files are still present in the S3 bucket. Only the index files should be.

Can rclone operate like rsync --archive --delete? If so, then update_remote_storage_with_rclone() should use those settings whenever rsync is. For example, the s3cmd code used --delete-removed --delete-after. It would be good to also have --delete-after if rclone has that.