uni04delta: set IronicDefaultNetworkInterface

For IPv6 we should use the "neutron" interface as the default
network interface in ironic conductor config.

This change ensures this is set for the uni04delta-ipv6 OSP17
cloud as well as in the RHOSO cloud.

Jira: OSPRH-20021

Author: hjensas

scenarios/uni04delta-ipv6/config_download.yaml

@@ -111,3 +111,4 @@ parameter_defaults:
     IronicNetwork: ironic
     IronicInspectorNetwork: ironic
   IronicCleaningDiskErase: metadata
+  IronicDefaultNetworkInterface: neutron

tests/roles/ironic_adoption/defaults/main.yaml

@@ -14,6 +14,13 @@ ironic_patch: |
       template:
         rpcTransport: oslo
         databaseInstance: openstack
+        customServiceConfig: |
+          [DEFAULT]
+          {% if ipv6_enabled | default(false) -%}
+          default_network_interface=neutron
+          {%- else -%}
+          default_network_interface=flat
+          {%- endif %}
         ironicAPI:
           replicas: 1
           override: