Pass NeutronMechanismDrivers parameter to prepare

This change is part of the proposal to use the value of
NeutronMechanismDrivers to determine what neutron images to prepare
(specifically whether the Opendaylight or OVN images should be
prepared).

Change-Id: I1fd78fd1eeb071788fc23ba343915ce7d6d14f02
Partial-Bug: #1794103
(cherry picked from commit 6450d206c6)

puppet/services/container-image-prepare.j2.yaml

@@ -47,6 +47,12 @@ parameters:
     type: comma_delimited_list
     default: []
 
+  NeutronMechanismDrivers:
+    default: 'openvswitch'
+    description: |
+        The mechanism drivers for the Neutron tenant network.
+    type: comma_delimited_list
+
 {% for role in roles %}
   # Parameters generated for {{role.name}} Role
   {{role.name}}Services:
@@ -89,6 +95,7 @@ outputs:
                 parameter_defaults:
                   ContainerImagePrepare: {get_param: ContainerImagePrepare}
                   DockerInsecureRegistryAddress: {get_param: DockerInsecureRegistryAddress}
+                  NeutronMechanismDrivers: {get_param: NeutronMechanismDrivers}
 {% for role in roles %}
                   {{role.name}}Services: {get_param: {{role.name}}Services}
                   {{role.name}}Count: {get_param: {{role.name}}Count}