Override image repository because kubeadm of Kubernetes v1.23.15 trie…

…s to pull the official image incorrectly

While kubeadm is buggy (kubernetes/kubernetes#114978) and tries to download the CoreDNS image despite us skipping that addon (kubernetes/kubeadm#2603), we try to use the new official repository already. This fixes `kubeadm join` for new Kubernetes versions and therefore avoids stuck node upgrades. CAPI propagates this value before attempting the node upgrade.

helm/cluster-aws/templates/_control_plane.tpl

@@ -52,6 +52,7 @@ spec:
       name: {{ include "resource.default.name" $ }}-control-plane-{{ include "hash" (dict "data" (include "bastion-awsmachinetemplate-spec" $) "global" .) }}
   kubeadmConfigSpec:
     clusterConfiguration:
+      imageRepository: registry.k8s.io {{- /* Temporary so that `kubeadm join` keeps working (https://github.com/giantswarm/roadmap/issues/1669, https://github.com/kubernetes/kubernetes/pull/114978), will later be replaced by Giant Swarm repo via https://github.com/giantswarm/roadmap/issues/1722 */}}
       apiServer:
         timeoutForControlPlane: 20m
         certSANs: