Fix etcd client generation (#10769)

* ci: redefine multinode to node-etcd-client

This should allow to catch several class of problem rather than just
one -> from network plugin such as calico or cilium talking directly to
the etcd.

* Dynamically define etcd host range

This has two benefits:
- We don't play the etcd role twice for no reason
- We have access to the whole cluster (if needed) to use things like
  group_by.

tests/files/packet_ubuntu22-calico-etcd-datastore.yml

@@ -1,7 +1,7 @@
 ---
 # Instance settings
 cloud_image: ubuntu-2204
-mode: multinode
+mode: node-etcd-client
 vm_memory: 1600Mi
 
 # Kubespray settings