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/action/TransportStartTransformAction.java
import org.elasticsearch.health.HealthStatus;
import org.elasticsearch.persistent.PersistentTasksCustomMetadata;
import org.elasticsearch.persistent.PersistentTasksService;
import org.elasticsearch.rest.RestStatus;
import org.elasticsearch.tasks.Task;
import org.elasticsearch.threadpool.ThreadPool;
import org.elasticsearch.transport.TransportService;
import org.elasticsearch.xpack.core.ClientHelper;
import org.elasticsearch.xpack.core.transform.TransformMessages;
import org.elasticsearch.xpack.core.transform.action.StartTransformAction;
import org.elasticsearch.xpack.core.transform.action.ValidateTransformAction;
import org.elasticsearch.xpack.core.transform.transforms.AuthorizationState;
import org.elasticsearch.xpack.core.transform.transforms.TransformConfig;
import org.elasticsearch.xpack.core.transform.transforms.TransformState;
import org.elasticsearch.xpack.core.transform.transforms.TransformTaskParams;
import org.elasticsearch.xpack.core.transform.transforms.TransformTaskState;
import org.elasticsearch.xpack.transform.TransformExtensionHolder;
import org.elasticsearch.xpack.transform.TransformServices;
import org.elasticsearch.xpack.transform.notifications.TransformAuditor;
import org.elasticsearch.xpack.transform.persistence.AuthorizationStatePersistenceUtils;
import org.elasticsearch.xpack.transform.persistence.TransformConfigManager;
import org.elasticsearch.xpack.transform.persistence.TransformIndex;
import org.elasticsearch.xpack.transform.transforms.TransformNodes;
import org.elasticsearch.xpack.transform.transforms.TransformTask;
import java.util.function.Consumer;
import java.util.function.Predicate;
import static org.elasticsearch.action.ValidateActions.addValidationError;
import static org.elasticsearch.core.Strings.format;
import static org.elasticsearch.xpack.core.transform.TransformMessages.CANNOT_START_FAILED_TRANSFORM;
public class TransportStartTransformAction extends TransportMasterNodeAction<StartTransformAction.Request, StartTransformAction.Response> {