Move host_architecture to kubespray-defaults (#5811)

The variable is defined in `kubernetes/preinstall` role and used in several roles. Since `kubernetes/preinstall` is not always included when `ansible-playbook` is run with tag selectors (see #5734 for reason), they will fail, or individual roles must copy the same fact definitions (as in #3846). Moving the definition to the always-included `kubespray-defaults` role will resolve the dependency problem.

roles/kubespray-defaults/defaults/main.yaml

@@ -539,3 +539,14 @@ etcd_config_dir: /etc/ssl/etcd
 etcd_cert_dir: "{{ etcd_config_dir }}/ssl"
 
 typha_enabled: false
+
+_host_architecture_groups:
+  x86_64: amd64
+  aarch64: arm64
+  armv7l: arm
+host_architecture: >-
+  {%- if ansible_architecture in _host_architecture_groups -%}
+  {{ _host_architecture_groups[ansible_architecture] }}
+  {%- else -%}
+  {{ ansible_architecture }}
+  {%- endif -%}