Minor cleanups of CoreDNS issues and CI job (#4719)

* Minor cleanups

* Add comment in docs that nodelocaldns cache is enabled by default

roles/kubernetes-apps/ansible/tasks/cleanup_dns.yml

@@ -7,6 +7,16 @@
     resource: "deploy"
     state: absent
   when:
-    - kubeadm_init is defined
-    - kubeadm_init.changed|default(false)
+    - dns_mode in ['coredns', 'coredns_dual']
+    - inventory_hostname == groups['kube-master'][0]
+
+- name: Kubernetes Apps | Delete kubeadm Kube-DNS service
+  kube:
+    name: "kube-dns"
+    namespace: "kube-system"
+    kubectl: "{{ bin_dir }}/kubectl"
+    resource: "svc"
+    state: absent
+  when:
+    - dns_mode in ['coredns', 'coredns_dual']
     - inventory_hostname == groups['kube-master'][0]