### 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
createCheckpointException
                            )
                        );
                    })
                ),
                getCheckPointException -> {
                    logger.warn(() -> "[" + getJobId() + "] failed to retrieve checkpoint.", getCheckPointException);
                    listener.onFailure(
                        new RuntimeException(
                            "Failed to retrieve checkpoint due to: " + getCheckPointException.getMessage(),
                            getCheckPointException
                        )
                    );
                }
            )
        );
    }
    @Override
    protected void onStart(long now, ActionListener<Boolean> listener) {
        if (context.getTaskState() == TransformTaskState.FAILED) {
            logger.debug("[{}] attempted to start while failed.", getJobId());
            listener.onFailure(new ElasticsearchException("Attempted to start a failed transform [{}].", getJobId()));
            return;
        }
        ActionListener<Void> finalListener = ActionListener.wrap(r -> {
            try {
                
                if (pageSize == 0) {
                    configurePageSize(getConfig().getSettings().getMaxPageSearchSize());
                }