ci: Update dyndns test for Fedora 42 and RHEL 10

Dyndns test needs to detect network interface name to work properly.
Instead of defaulting to eth0 we use real name for the test.

Author: jakub-vavra-cz

tests/tests_full_integration_dyndns.yml

@@ -62,21 +62,22 @@
 
 - name: Ensure that the role configures dynamic dns
   hosts: client
+  gather_facts: true
   tasks:
     - name: Run the integration
       when: "'ad' in groups and groups['ad']"
       block:
         - name: Debug dyndns settings
           debug:
             msg: >-
-              Interface {{ _ad_dyndns_iface | default('eth0') }} and server
+              Interface {{ _ad_dyndns_iface | default(ansible_default_ipv4.interface) }} and server
               : {{ hostvars[groups['ad'][0]].ansible_host }}
         - name: Run the system role with proper config
           include_role:
             name: linux-system-roles.ad_integration
           vars:
             ad_dyndns_server: "{{ hostvars[groups['ad'][0]].ansible_host }}"
-            ad_dyndns_iface: "{{ _ad_dyndns_iface | default('eth0') }}"
+            ad_dyndns_iface: "{{ _ad_dyndns_iface | default(ansible_default_ipv4.interface) }}"
             ad_dyndns_auth: "none"
             ad_dyndns_update: true
             ad_dyndns_refresh_interval: 60