refactor(configuration): centralize DNS list variables in network dispatch

roles/configuration/tasks/network_alpine.yml

@@ -1,7 +1,5 @@
 ---
 - name: Write Alpine network interfaces
-  vars:
-    configuration_dns_list: "{{ system_cfg.network.dns.servers | default([]) }}"
   ansible.builtin.copy:
     dest: /mnt/etc/network/interfaces
     mode: "0644"
@@ -25,9 +23,6 @@
       {% endfor %}
 
 - name: Set Alpine DNS resolvers
-  vars:
-    configuration_dns_list: "{{ system_cfg.network.dns.servers | default([]) }}"
-    configuration_dns_search: "{{ system_cfg.network.dns.search | default([]) }}"
   when: configuration_dns_list | length > 0 or configuration_dns_search | length > 0
   ansible.builtin.copy:
     dest: /mnt/etc/resolv.conf