Fix kube_hostname_override inconsistencies (#4185)

roles/kubernetes/kubeadm/defaults/main.yml

@@ -1,3 +1,10 @@
 ---
 # discovery_timeout modifies the discovery timeout
 discovery_timeout: 5m0s
+
+# If non-empty, will use this string as identification instead of the actual hostname
+kube_override_hostname: >-
+  {%- if cloud_provider is defined and cloud_provider in [ 'aws' ] -%}
+  {%- else -%}
+  {{ inventory_hostname }}
+  {%- endif -%}