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/etcd/tasks/main.yml

@@ -1,19 +1,4 @@
 ---
-- name: set architecture_groups
-  set_fact:
-    architecture_groups:
-      x86_64: amd64
-      aarch64: arm64
-
-- name: ansible_architecture_rename
-  set_fact:
-    host_architecture: >-
-      {%- if ansible_architecture in architecture_groups -%}
-      {{ architecture_groups[ansible_architecture] }}
-      {%- else -%}
-       {{ ansible_architecture }}
-      {% endif %}
-
 - include_tasks: check_certs.yml
   when: cert_management == "script"
   tags: