Add datacenter node setup scripts (#5517)

automerge

net/datacenter-node-install/set-hostname.sh

@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+
+HERE="$(dirname "$0")"
+
+# shellcheck source=net/datacenter-node-install/utils.sh
+source "$HERE"/utils.sh
+
+ensure_env || exit 1
+
+set -xe
+
+echo "preserve_hostname: false" > /etc/cloud/cloud.cfg.d/99-disable-preserve-hostname.cfg
+systemctl restart cloud-init
+hostnamectl set-hostname "$1"