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
@Override
            public void onFailure(Exception e) {
                logger.error(
                    "["
                        + transformId
                        + "] Failed to cancel persistent task that could "
                        + "not be assigned due to ["
                        + exception.getMessage()
                        + "]",
                    e
                );
                onFailure.accept(exception);
            }
        });
    }
    private void waitForTransformTaskStarted(
        String taskId,
        TransformTaskParams params,
        TimeValue timeout,
        ActionListener<Boolean> listener
    ) {
        TransformPredicate predicate = new TransformPredicate();
        persistentTasksService.waitForPersistentTaskCondition(
            taskId,
            predicate,
            timeout,
            new PersistentTasksService.WaitForPersistentTaskListener<TransformTaskParams>() {
                @Override
                public void onResponse(PersistentTasksCustomMetadata.PersistentTask<TransformTaskParams> persistentTask) {
                    if (predicate.exception != null) {