sysprep: Remove could-init

Cloud images for VMs usually are prepared to be used with
cloud-init. Because lago does not utilize could-init, it
should be removed to avoid waiting could-init for
configuration during booting.

This change improves the usage of cloud images in lago.

lago/templates/sysprep-base.j2

@@ -10,3 +10,4 @@ upload {{ public_key }}:/root/.ssh/authorized_keys
 chmod 0600:/root/.ssh/authorized_keys
 run-command chown root:root /root/.ssh/authorized_keys
 {% endif -%}
+uninstall cloud-init