ts-host-install,preseed_create: Do lvm vgextend at install time

ts-host-install,preseed_create: Do lvm vgextend at install time

When there's more than one disk, like the "pinot?" machine, the name
assigned to e.g. "sda" may change after a reboot, at least when
installing Debian Bookworm, which is using Linux 6.1.

I believe Linux probes disk controller in parallel and assign "sda"
to the first controller to respond, or something like that, so disk
aren't assigned a name in a predictable order.

So, instead of extending lvm volume group to a new disk on reboot, do
that at install time when we know that lvm is on sda.

Alternatively, we could try to set "d-i partman-auto/disk" with a list
of all disk, but that would mean knowing all the disk before starting
the machine.

This new shell script in /lib/partman/finish.d/ should work in all
debian, so replace the script in ts-host-install by this new one.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>