networking: Remove support for specifying DNS servers

Redundant since this commit:
bdd538ec

 ("Use unbound for rspamd DNS resolving")
Signed-off-by: Leonidas Spyropoulos <artafinde@gmail.com>

host_vars/mail.archlinux.org/misc

@@ -10,6 +10,5 @@ fail2ban_jails:
 
 ipv4_address: "95.216.189.61"
 ipv6_address: "2a01:4f9:c010:3052::1"
-dns_servers: ["127.0.0.1"]
 wireguard_address: 10.0.0.14
 wireguard_public_key: +RJ/ZNRmw2uCHxSjJZHftk7lWUl5nJ6VSZww8GPwhEI=

roles/networking/defaults/main.yml

 ---
 chroot_path: ""
 network_interface: "e*"
-dns_servers: []

roles/networking/tasks/main.yml

 ---
-- name: set fact for local dns resolver in use
-  set_fact:
-    host_has_local_dns_resolver: "{{ dns_servers|length == 1 and '127.0.0.1' in dns_servers }}"
-
 - name: configure network (static)
   template: src=10-static-ethernet.network.j2 dest={{ chroot_path }}/etc/systemd/network/10-static-ethernet.network owner=root group=root mode=0644
   notify:

roles/networking/templates/10-static-ethernet.network.j2

@@ -2,9 +2,6 @@
 Name={{ network_interface }}
 
 [Network]
-{% for server in dns_servers %}
-DNS={{server}}
-{% endfor %}
 Gateway={{ ipv4_gateway }}
 {% if ipv6_gateway is defined %}
 Gateway={{ ipv6_gateway }}