ci: Switch to pkgs.k8s.io

The kubernetes repositories at packages.cloud.google.com have been removed
as announced in [1]. Switch to the new infrastructure at pkgs.k8s.io. Use
the latest available version (v1.29).

[1] https://kubernetes.io/blog/2023/08/15/pkgs-k8s-io-introduction/ .

Fixes #5811

Signed-off-by: Greg Kurz <groug@kaod.org>

Author: gkurz

.ci/install_kubernetes.sh

@@ -25,11 +25,10 @@ if [ "$ID" == "ubuntu" ]; then
 		sudo -E apt purge kubelet -y
 	fi
 	sudo bash -c "cat <<EOF > /etc/apt/sources.list.d/kubernetes.list
-	deb http://packages.cloud.google.com/apt/ kubernetes-xenial-unstable main
+	deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.29/deb/ /
 EOF"
-
 	chronic sudo -E sed -i 's/^[ \t]*//' /etc/apt/sources.list.d/kubernetes.list
-	curl -fsSL https://dl.k8s.io/apt/doc/apt-key.gpg | sudo apt-key add -
+	curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.29/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg
 	chronic sudo -E apt update
 	chronic sudo -E apt install --allow-downgrades -y kubelet="$kubernetes_version" kubeadm="$kubernetes_version" kubectl="$kubernetes_version"
 elif [[ "$ID" =~ ^(alinux|centos|fedora|rhel)$ ]]; then