### 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/test/java/org/elasticsearch/xpack/core/DataTiersUsageTransportActionTests.java
IndexMetadata hotIndex2 = indexMetadata("hot-2", 1, 0, DataTier.DATA_HOT);
        IndexMetadata warmIndex1 = indexMetadata("warm-1", 1, 0, DataTier.DATA_WARM);
        IndexMetadata coldIndex1 = indexMetadata("cold-1", 1, 0, DataTier.DATA_COLD);
        IndexMetadata coldIndex2 = indexMetadata("cold-2", 1, 0, DataTier.DATA_COLD, DataTier.DATA_WARM); 
        IndexMetadata nonTiered = indexMetadata("non-tier", 1, 0); 
        ImmutableOpenMap.Builder<String, IndexMetadata> indicesBuilder = ImmutableOpenMap.builder();
        indicesBuilder.put("hot-1", hotIndex1);
        indicesBuilder.put("hot-2", hotIndex2);
        indicesBuilder.put("warm-1", warmIndex1);
        indicesBuilder.put("cold-1", coldIndex1);
        indicesBuilder.put("cold-2", coldIndex2);
        indicesBuilder.put("non-tier", nonTiered);
        ImmutableOpenMap<String, IndexMetadata> indices = indicesBuilder.build();
        Map<String, String> tiers = DataTiersUsageTransportAction.tierIndices(indices);
        assertThat(tiers.size(), equalTo(5));
        assertThat(tiers.get("hot-1"), equalTo(DataTier.DATA_HOT));
        assertThat(tiers.get("hot-2"), equalTo(DataTier.DATA_HOT));
        assertThat(tiers.get("warm-1"), equalTo(DataTier.DATA_WARM));
        assertThat(tiers.get("cold-1"), equalTo(DataTier.DATA_COLD));
        assertThat(tiers.get("cold-2"), equalTo(DataTier.DATA_COLD));
        assertThat(tiers.get("non-tier"), nullValue());
    }
    public void testCalculateStatsNoTiers() {
        
        DiscoveryNodes.Builder discoBuilder = DiscoveryNodes.builder();
        DiscoveryNode leader = newNode(0, DiscoveryNodeRole.MASTER_ROLE);
        discoBuilder.add(leader);
        discoBuilder.masterNodeId(leader.getId());
        DiscoveryNode dataNode1 = newNode(1, DiscoveryNodeRole.DATA_ROLE);
        discoBuilder.add(dataNode1);