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/init.pp

@@ -13,6 +13,7 @@ class rke2 (
   Array[String[1]]        $extra_config_files = $rke2::params::extra_config_files,
   Stdlib::HTTPUrl         $container_archive_source = $rke2::params::container_archive_source,
   Boolean                 $manage_registries = $rke2::params::manage_registries,
+  Hash                    $registries = $rke2::params::registries,
 ) inherits rke2::params {
 
   include rke2::install