### Elasticsearch Version

main

### Installed Plugins

_No response_

### Java Version

_bundled_

### OS Version

MacOS

### Problem Description

Currently, transform state persistence failures are being retried with a constant interval (`60s`).
This is different to how other types of errors are retried (exponential backoff).
We should implement exponential backoff for state persistence failures too.

### Steps to Reproduce

n/a

### Logs (if relevant)

_No response_
x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/transforms/ClientTransformIndexer.java
import org.elasticsearch.xpack.transform.checkpoint.CheckpointProvider;
import org.elasticsearch.xpack.transform.persistence.SeqNoPrimaryTermAndIndex;
import org.elasticsearch.xpack.transform.transforms.pivot.SchemaUtil;
import org.elasticsearch.xpack.transform.utils.ExceptionRootCauseFinder;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicReference;
import static org.elasticsearch.core.Strings.format;
class ClientTransformIndexer extends TransformIndexer {
    private static final TimeValue PIT_KEEP_ALIVE = TimeValue.timeValueSeconds(30);
    private static final Logger logger = LogManager.getLogger(ClientTransformIndexer.class);
    private final ParentTaskAssigningClient client;
    private final AtomicBoolean oldStatsCleanedUp = new AtomicBoolean(false);
    private final AtomicReference<SeqNoPrimaryTermAndIndex> seqNoPrimaryTermAndIndexHolder;
    private final ConcurrentHashMap<String, PointInTimeBuilder> namedPits = new ConcurrentHashMap<>();
    private volatile long pitCheckpoint;
    private volatile boolean disablePit = false;
    ClientTransformIndexer(
        ThreadPool threadPool,
        TransformServices transformServices,
        CheckpointProvider checkpointProvider,
        AtomicReference<IndexerState> initialState,
        TransformIndexerPosition initialPosition,
        ParentTaskAssigningClient client,
        TransformIndexerStats initialStats,
        TransformConfig transformConfig,
        TransformProgress transformProgress,