add conditional for vlan in oci vars

Author: William Graef

ocne/templates/oci_vars.j2

@@ -8,4 +8,6 @@ my_compartment_id: {{ my_compartment_id }}
 my_vcn_id: {{ my_vcn_id }}
 my_subnet_id: {{ my_subnet_id }}
 my_subnet_domain_name: {{ my_subnet_domain_name }}
-my_vlan_id: {{ my_vlan_id }}
+{% if use_vlan %}
+my_vlan_id: {{ my_vlan_id }}
+{% endif %}