* DEV: new S3 backup layout
Currently, with $S3_BACKUP_BUCKET of "bucket/backups", multisite backups
end up in "bucket/backups/backups/dbname/" and single-site will be in
"bucket/backups/".
Both _should_ be in "bucket/backups/dbname/"
- remove MULTISITE_PREFIX,
- always include dbname,
- method to move to the new prefix
- job to call the method
* SPEC: add tests for `VacateLegacyPrefixBackups` onceoff job.
Co-authored-by: Vinoth Kannan <vinothkannan@vinkas.com>
Andrew Schleifer