Add a warning for resizing servers booted from volumes

Story: 2010858
Task: 48521
Change-Id: Ib72da4d2c2b4bfbbdbc1e8302b65d240e4e1d459

Author: yukariatlas

openstackclient/compute/v2/server.py

@@ -4017,6 +4017,13 @@ def _show_progress(progress):
                 compute_client.flavors,
                 parsed_args.flavor,
             )
+            if not server.image:
+                self.log.warning(
+                    _(
+                        "The root disk size in flavor will not be applied "
+                        "while booting from a persistent volume."
+                    )
+                )
             compute_client.servers.resize(server, flavor)
             if parsed_args.wait:
                 if utils.wait_for_status(