feat(system-upgrade): Remove integrated reboot

This patch removes the integrated reboot from the upgrade plan, and
replaces it, by a reboot managed by kured.

References:
https://github.com/weaveworks/kured

infrastructure/system-upgrades/fedora.yaml

@@ -15,7 +15,7 @@ stringData:
     systemctl start --wait dnf-automatic-install.service
     systemctl enable clevis-luks-askpass.path
     if ! dnf needs-restarting --reboothint; then
-      systemctl reboot
+      touch /var/run/reboot-required
     fi
 ---
 apiVersion: upgrade.cattle.io/v1
@@ -40,10 +40,6 @@ spec:
   secrets:
     - name: fedora-dnf-upgrade
       path: /host/run/system-upgrade/secrets/fedora
-  drain:
-    deleteLocalData: true
-    ignoreDaemonSets: true
-    force: false
   channel: http://calver/weekly
   upgrade:
     image: registry.fedoraproject.org/fedora:35