private boolean parkedByProvisionedExpirer(Node node) {
        return node.history().event(History.Event.Type.parked)
                .map(History.Event::agent)
                .map(Agent.ProvisionedExpirer::equals)
                .orElse(false);
    }
This moves nodes of type {@link NodeType#host} from provisioned to parked if they have been in provisioned too long.
Parked hosts are deprovisioned as well, if too many hosts are being expired.

Only {@link NodeType#host} is moved because any number of nodes of that type can exist. Other node types such as
{@link NodeType#confighost} have a fixed number and thus cannot be replaced while the fixed number of nodes exist in
any state.

@author freva
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/maintenance/ProvisionedExpirer.java