I'm seeing quite a few of these in prod:

```
java.lang.NullPointerException: Cannot invoke "org.elasticsearch.xpack.core.transform.transforms.TransformState.getTaskState()" because "transformState" is null
    at org.elasticsearch.xpack.transform.TransformUsageTransportAction.masterOperation(TransformUsageTransportAction.java:106) ~[?:?]
    at org.elasticsearch.xpack.transform.TransformUsageTransportAction.masterOperation(TransformUsageTransportAction.java:55) ~[?:?]
    at org.elasticsearch.action.support.master.TransportMasterNodeAction.executeMasterOperation(TransportMasterNodeAction.java:124) ~[elasticsearch-8.9.0.jar:?]
    at org.elasticsearch.action.support.master.TransportMasterNodeAction$AsyncSingleAction.lambda$doStart$3(TransportMasterNodeAction.java:235) ~[elasticsearch-8.9.0.jar:?]
    at org.elasticsearch.action.ActionRunnable$3.doRun(ActionRunnable.java:72) ~[elasticsearch-8.9.0.jar:?]
    at org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingAbstractRunnable.doRun(ThreadContext.java:983) ~[elasticsearch-8.9.0.jar:?]
    at org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:26) ~[elasticsearch-8.9.0.jar:?]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144) ~[?:?]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642) ~[?:?]
    at java.lang.Thread.run(Thread.java:1623) ~[?:?]
```

`org.elasticsearch.persistent.PersistentTasksCustomMetadata.PersistentTask#getState` is declared `@Nullable` but this case is not handled properly by the usage action.
x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/TransformUsageTransportAction.java
import org.elasticsearch.protocol.xpack.XPackUsageRequest;
import org.elasticsearch.search.aggregations.AggregationBuilders;
import org.elasticsearch.search.aggregations.Aggregations;
import org.elasticsearch.search.aggregations.bucket.filter.Filters;
import org.elasticsearch.search.aggregations.bucket.filter.FiltersAggregator;
import org.elasticsearch.tasks.Task;
import org.elasticsearch.threadpool.ThreadPool;
import org.elasticsearch.transport.TransportService;
import org.elasticsearch.xcontent.ParseField;
import org.elasticsearch.xpack.core.ClientHelper;
import org.elasticsearch.xpack.core.action.XPackUsageFeatureAction;
import org.elasticsearch.xpack.core.action.XPackUsageFeatureResponse;
import org.elasticsearch.xpack.core.action.XPackUsageFeatureTransportAction;
import org.elasticsearch.xpack.core.transform.TransformFeatureSetUsage;
import org.elasticsearch.xpack.core.transform.TransformField;
import org.elasticsearch.xpack.core.transform.transforms.TransformConfig;
import org.elasticsearch.xpack.core.transform.transforms.TransformIndexerStats;
import org.elasticsearch.xpack.core.transform.transforms.TransformState;
import org.elasticsearch.xpack.core.transform.transforms.TransformTaskState;
import org.elasticsearch.xpack.core.transform.transforms.persistence.TransformInternalIndexConstants;
import org.elasticsearch.xpack.transform.transforms.TransformTask;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.stream.Stream;
import static java.util.stream.Collectors.toMap;
public class TransformUsageTransportAction extends XPackUsageFeatureTransportAction {
    private static final Logger logger = LogManager.getLogger(TransformUsageTransportAction.class);