Group entries by tenant so each tenant gets its own GFS ladder.
Backup filenames follow ${prefix}${site_or_tenant}-${date}.zip
(see create_backup()). The grouping key is the basename with the
trailing -<date>.zip stripped; entries that do not match the
pattern fall into their full basename as a conservative default
(they are then subject to keep_min within their own group).
Group entries by tenant so each tenant gets its own GFS ladder.
Backup filenames follow
${prefix}${site_or_tenant}-${date}.zip(see create_backup()). The grouping key is the basename with the trailing-<date>.zipstripped; entries that do not match the pattern fall into their full basename as a conservative default (they are then subject to keep_min within their own group).