Adjusting the scale doesn't take the shortest path

[tnozicka]

Is this a bug report or feature request?

• Feature Request

What should the feature do: The operator should stop scaling up if a new desired state has less members.

What is use case behind this feature: Say we have a scylla cluster with 3 nodes and want to adjust members to 5 but accidentally put 55 there. The controller will create 55 services which is fine but when we correct ourselves and change the members to 5, the controller will first scale up to 55 nodes and only then goes back to 5. In the worst case your infra won't be big enough to scale to 55 instances and you'll get stuck.

Additional Information: We are creating the services ahead of time which is fine but we need to make sure we stop scaling up as soon as we can and somehow differentiate the services that never had a bootstrapped node (which may be hard).