Significantly reduce memory requirements

Canal runs more pods and upgrades need a bit of extra
room to load new pods in and get the old ones out.

roles/kubernetes/master/tasks/pre-upgrade.yml

@@ -38,7 +38,7 @@
   environment:
     ETCDCTL_API: 2
   register: old_data_exists
-  delegate_to: "{{groups['kube-master'][0]}}"
+  delegate_to: "{{groups['etcd'][0]}}"
   when: kube_apiserver_storage_backend == "etcd3"
   failed_when: false