Jenkins: Add cloud-image-utils into 'libvirt' slave

Change-Id: Idf9712c5502971ba3902f35708ed9ecaee7fe158
diff --git a/jenkins/slave/libvirt.yml b/jenkins/slave/libvirt.yml
index e40b841..4ebaae2 100644
--- a/jenkins/slave/libvirt.yml
+++ b/jenkins/slave/libvirt.yml
@@ -14,6 +14,9 @@
           version: latest
         libvirt-bin:
           version: latest
+        # Reguired to simplify building custom cloud-init.iso
+        cloud-image-utils:
+          version: latest
   # Ensure FORWARD chain to be ACCEPT to avoid issue when running with docker
   # 1.13 and newer that sets chain to DROP, see:
   #   https://github.com/docker/docker/pull/28257