Make create_vm work on all OS versions in use

Makes it work with the same cloudinit code on Ubuntu 20.04 by mounting
it from a custom ISO as CD-ROM

site-cookbooks/kosmos_kvm/recipes/host.rb

@@ -5,6 +5,11 @@
 
 package %w(virtinst libvirt-daemon-system libvirt-clients)
 
+# Required on legacy hosts (Ubuntu 20.04) to build the NoCloud seed ISO
+# via cloud-localds. Modern virt-install (>= 4.0.0, Ubuntu >= 22.04)
+# handles cloud-init natively via --cloud-init and does not need it.
+package "cloud-image-utils" if node["platform_version"].to_f < 22.04
+
 directory "/var/lib/libvirt/images/base" do
   recursive true
   owner "libvirt-qemu"
@@ -24,7 +29,10 @@ end
 template "/usr/local/sbin/create_vm" do
   source "create_vm.erb"
   mode "0750"
-  variables base_image_path: node["kosmos_kvm"]["host"]["qemu_base_image"]["path"]
+  variables(
+    base_image_path: node["kosmos_kvm"]["host"]["qemu_base_image"]["path"],
+    modern_virt_install: node["platform_version"].to_f >= 22.04
+  )
 end
 
 firewall_rule 'ssh-alt-port' do