### Elasticsearch Version

8.1.2

### Installed Plugins

_No response_

### Java Version

_bundled_

### OS Version

ESS on Azure

### Problem Description

The `_xpack/usage` API reports the size of the data set per data tier. However, it uses the local disk size as the metric it reports on and this is 0 (zero) for partially mounted indices, hiding the size of the data set mounted on the frozen tier.

We should switch to using the `total_data_set_size` metric that was introduced when we added the frozen tier/partially mounted indices.

### Steps to Reproduce

Mount a partially mounted index on a dedicated frozen tier. Use the `_xpack/usage` API and see that no (or very little) data is reported on frozen tier.

### Logs (if relevant)

_No response_
x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/DataTiersUsageTransportAction.java
import org.elasticsearch.index.store.StoreStats;
import org.elasticsearch.protocol.xpack.XPackUsageRequest;
import org.elasticsearch.search.aggregations.metrics.TDigestState;
import org.elasticsearch.tasks.Task;
import org.elasticsearch.threadpool.ThreadPool;
import org.elasticsearch.transport.TransportService;
import org.elasticsearch.xpack.core.action.XPackUsageFeatureAction;
import org.elasticsearch.xpack.core.action.XPackUsageFeatureResponse;
import org.elasticsearch.xpack.core.action.XPackUsageFeatureTransportAction;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.stream.StreamSupport;
public class DataTiersUsageTransportAction extends XPackUsageFeatureTransportAction {
    private final Client client;
    @Inject
    public DataTiersUsageTransportAction(
        TransportService transportService,
        ClusterService clusterService,
        ThreadPool threadPool,
        ActionFilters actionFilters,
        IndexNameExpressionResolver indexNameExpressionResolver,
        Client client
    ) {
        super(
            XPackUsageFeatureAction.DATA_TIERS.name(),
            transportService,
            clusterService,