private boolean hasScaledIn(Duration period) {
        if (cluster.lastScalingEvent().isEmpty()) return false;
        var lastCompletion = cluster.lastScalingEvent().get().completion();
        if (lastCompletion.isEmpty()) return true; // Ongoing
        return lastCompletion.get().isAfter(clock.instant().minus(period));
    }
Returns the ideal load across the nodes of this such that each node will be at ideal load
if one of the nodes go down.
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/autoscale/ClusterModel.java