Match Fedora Server's partitioning
    
    The max size of 3GB is pretty restrictive for most bare metal installs where we
    expect people to have at least one large physical drive. This gives a lot more
    headroom for things that may be stored in `/` like e.g. the systemd journal.
    
    The max size of `15GB` ensures that if the user wants to make other LVs, there's
    enough space in the VG to do so.
    
    Note this deletes the `/boot` override; while I don't like the new Blivet
    default of `1G`, it's a messy topic, and I don't think it's worth carrying
    an override in the baremetal path just for that.
    
    Note we also explicitly start matching the Fedora Server default of XFS,
    with the same rationale; there's a [long thread](https://lists.fedoraproject.org/archives/list/server@lists.fedoraproject.org/thread/W4KWEEKADZDCAFK4XJYEJG34DZLTC3BB/)
    
    For AH, we've been using XFS by default, this just ensures it's used
    across all filesystems by default.
    
    One specific reason why XFS is good over ext4 is support for dynamic inodes is
    really quite nice when using `overlayfs` and containers.