fix(virtualization): add XML safety attributes and switch xen to virtio

templates/xen.cfg.j2

@@ -12,7 +12,7 @@ disk = [
 ]
 vif = [
 {%- for iface in system_cfg.network.interfaces -%}
-  'bridge={{ iface.bridge }},model=e1000'{% if not loop.last %}, {% endif %}
+  'bridge={{ iface.bridge }},model=virtio'{% if not loop.last %}, {% endif %}
 {%- endfor -%}
 ]
 boot = "{{ 'dc' if xen_installer_media_enabled | bool else 'c' }}"