proxmox/packer: Create Debian bookworm images

Related to sysadm-environment#5015 (closed)

1. I created 2 VMs with the new templates.
   Puppet agent failed to connect Puppet server:

   [...]
   module.gsa-test-zfs.proxmox_vm_qemu.node (remote-exec): Error: Could not download CA certificate: Bad Request
   module.gsa-test-zfs.proxmox_vm_qemu.node (remote-exec): Error: Could not download CA certificate: Bad Request
   module.gsa-test-zfs.proxmox_vm_qemu.node (remote-exec): Node provisionned!
   module.gsa-test-zfs.proxmox_vm_qemu.node: Creation complete after 1m43s [id=uffizi/qemu/149]
   module.gsa-test.proxmox_vm_qemu.node (remote-exec): Error: Could not download CA certificate: Bad Request
   module.gsa-test.proxmox_vm_qemu.node (remote-exec): Error: Could not download CA certificate: Bad Request
   module.gsa-test.proxmox_vm_qemu.node (remote-exec): Node provisionned!
   module.gsa-test.proxmox_vm_qemu.node: Creation complete after 1m43s [id=uffizi/qemu/148]
   
   Apply complete! Resources: 2 added, 0 changed, 0 destroyed.
   [...]

See 4778#note_146917.

2. I changed the installer user UID in the preseed file from 999 to 899:

   /var/log/installer/syslog

   Aug 30 09:10:13 user-setup: adduser: The GID 999 is already in use.
   [...]
   Aug 30 11:10:13 chpasswd[8791]: pam_unix(chpasswd:chauthtok): user "installer" does not exist in /etc/passwd
   [...]
   Aug 30 09:10:13 finish-install: warning: /usr/lib/finish-install.d/06user-setup returned error code 1

   awk '/999/' /etc/group
   systemd-journal:x:999: