kubernetes/preinstall: dns setting cleanup(dhclient, resolvconf)

We use a lot of facts where variables are enough, and format too early,
which prevent reusing the variables in different contexts.

- Moves set_fact variables to the vars directory, remove unnecessary
 intermediate variables, and render them at usage sites to only do logic
 on native Ansible/Jinja lists.
- Use defaults/ rather than default filters for several variables.

roles/kubernetes/preinstall/tasks/0060-resolvconf.yml

@@ -7,10 +7,9 @@
   blockinfile:
     path: "{{ resolvconffile }}"
     block: |-
-      {% for item in [domainentry] + [searchentries] -%}
-      {{ item }}
-      {% endfor %}
-      {% for item in nameserverentries.split(',') %}
+      domain {{ dns_domain }}
+      search {{ (default_searchdomains + searchdomains) | join(' ') }}
+      {% for item in nameserverentries %}
       nameserver {{ item }}
       {% endfor %}
       options ndots:{{ ndots }} timeout:{{ dns_timeout | default('2') }} attempts:{{ dns_attempts | default('2') }}