Remove secondary-disk discovery and whole-disk ZFS creation from the
installer. New installations now always create a sparse ZFS loop-file
pool from free space on /, while existing vpsmgr pools are still adopted.
The installer no longer scans, selects, formats, or modifies devices such
as /dev/vdb, including virtual ISO/CD devices.
Update storage documentation and keep the existing reclaim, pool sizing,
and ZFS quota behavior.
Co-authored-by: CommandCodeBot <noreply@commandcode.ai>
