Cleanup NetworkManager Dummy Interface

Reproducer cleanup fails with permission denied error when trying
to remove NetworkManager dummy interface connection files created
by libvirt_manager role.

The framework creates NetworkManager dummy interface connection files
(e.g., dummy-fssqrsss.nmconnection) during libvirt network setup but
fails to properly clean them up during reproducer cleanup, resulting
in permission denied errors.

This PR will solve this issue by adding tasks to find and remove those
dummy interface in the clean_layout.yml playbook.

testresult https://softwarefactory-project.io/zuul/t/rdoproject.org/build/c48f86a9b817405dbd058fa87ca9135e/log/job-output.txt#2160-2169

Author: bshewale

roles/libvirt_manager/tasks/clean_layout.yml

@@ -166,6 +166,21 @@
         state: absent
       loop: "{{ cleanup_nets }}"
 
+    - name: Find dummy interface connection files
+      ansible.builtin.find:
+        paths: /etc/NetworkManager/system-connections/
+        patterns: "dummy*"
+        file_type: file
+      register: dummy_connections
+
+    - name: Remove dummy interface connections
+      become: true
+      ansible.builtin.file:
+        path: "{{ item.path }}"
+        state: absent
+      loop: "{{ dummy_connections.files }}"
+      when: dummy_connections.matched > 0
+
     - name: Clean firewalld libvirt zone
       become: true
       ansible.posix.firewalld: