### Description

Currently, when we execute retention policy, we also refresh the destination index by setting:
```
setRefresh(true)
```
on the DBQ request.
This can cause permission errors which are surprising to the user as the permissions are not required when the transform starts:
```
task encountered irrecoverable failure: org.elasticsearch.ElasticsearchSecurityException: action [indices:admin/refresh] is unauthorized for user [found-internal-kibana4-server] with roles [kibana_system,found-internal-kibana4-server] on indices [logs-cloud_security_posture.findings_latest-default], this action is granted by the index privileges [maintenance,manage,all]
```

We still want the user to have the permissions to delete the documents. But we should execute `refresh` as the system user.
x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/transforms/TransformIndexer.java
IndexerState state = getState();
            
            if (state == IndexerState.STARTED && context.shouldStopAtCheckpoint() != shouldStopAtCheckpoint) {
                IndexerState newIndexerState = IndexerState.STARTED;
                TransformTaskState newtaskState = context.getTaskState();
                
                
                
                if (shouldStopAtCheckpoint && initialRun()) {
                    newIndexerState = IndexerState.STOPPED;
                    newtaskState = TransformTaskState.STOPPED;
                    logger.debug("[{}] transform is at a checkpoint, initiating stop.", transformConfig.getId());
                } else {
                    context.setShouldStopAtCheckpoint(shouldStopAtCheckpoint);
                }
                final TransformState newTransformState = new TransformState(
                    newtaskState,
                    newIndexerState,
                    getPosition(),
                    context.getCheckpoint(),
                    context.getStateReason(),
                    getProgress(),
                    null,
                    newIndexerState == IndexerState.STARTED
                );
                
                
                CountDownLatch latch = new CountDownLatch(1);
                logger.debug("[{}] persisting stop at checkpoint", getJobId());
                persistState(newTransformState, ActionListener.wrap(() -> latch.countDown()));