Fix list concatenation of routes in bond-with-vlan

We are passing a list of routes to concatenate. This list
was nested in another list, causing an invalid configuration.

Closes-Bug: #1793838
Change-Id: I7a8bc5d2171905237fe36d5ccad853f838c9bffc
(cherry picked from commit 6deb54c5a1)

network/config/bond-with-vlans/role.role.j2.yaml

@@ -130,9 +130,9 @@ resources:
                       get_param: {{network.name}}IpSubnet
                   routes:
                     list_concat_unique:
-                      - - get_param: {{network.name}}InterfaceRoutes
+                      - get_param: {{network.name}}InterfaceRoutes
 {%- if network.name in role.default_route_networks %}
-                        - default: true
+                      - - default: true
                           next_hop:
                             get_param: {{network.name}}InterfaceDefaultRoute
 {%- endif %}