Convert RKE2 registries to template, disable default endpoints (#474)

## Summary
- Replace static `registries.yaml` with EPP template driven by `rke2::registries` hash
- Add `disable-default-registry-endpoint: true` to all mirrors — RKE2 will only use artifactapi and never fall back to upstream registries
- Registry configuration now fully managed via hiera data (`roles/infra/k8s.yaml`)

Reviewed-on: #474
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>

modules/rke2/manifests/params.pp

@@ -13,4 +13,5 @@ class rke2::params (
   Array[String[1]]        $extra_config_files = [],
   Stdlib::HTTPUrl         $container_archive_source = 'https://github.com/rancher/rke2/releases/download',
   Boolean                 $manage_registries = false,
+  Hash                    $registries = {},
 ) {}