### 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/TransformIndexer.java
@Override
    protected float getMaxDocsPerSecond() {
        return docsPerSecond;
    }
    @Override
    protected boolean triggerSaveState() {
        
        if (saveStateListeners.get() != null) {
            return true;
        }
        return TimeUnit.NANOSECONDS.toMillis(getTimeNanos()) > lastSaveStateMilliseconds + DEFAULT_TRIGGER_SAVE_STATE_INTERVAL_MS;
    }
    public TransformConfig getConfig() {
        return transformConfig;
    }
    public boolean isContinuous() {
        return getConfig().getSyncConfig() != null;
    }
    public Map<String, String> getFieldMappings() {
        return fieldMappings;
    }
    public TransformProgress getProgress() {
        return progress;
    }
    public TransformCheckpoint getLastCheckpoint() {
        return lastCheckpoint;
    }
    public TransformCheckpoint getNextCheckpoint() {
        return nextCheckpoint;
    }