config: fix dropping description on parsing special cloud init section

config: fix dropping description on parsing special cloud init section

we now always write out a new clouding special section on start (to
be fixed) independent of any cloudinit drive/config configured or
not, and thus always run into that section after a VM started with
the new qemu-server installed, which in turn set the description
always to undef.

Fixes: 95a5135 ("cloudinit: add cloudinit section for current generated config.")
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>