fix: add local registry cache for rebuilds

ansible/roles/k3s-registry-mirror/templates/registries.yaml.j2

@@ -0,0 +1,6 @@
+mirrors:
+{% for registry, mirror in k3s_registry_mirrors.items() %}
+  "{{ registry }}":
+    endpoint:
+      - "http://{{ k3s_registry_mirror_host }}:{{ mirror.port }}"
+{% endfor %}