### 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
* gh#81252 transform can fail if an index gets deleted during searches
                 *
                 * Until proper checkpoint searches (seq_id per shard) are possible, we have to query
                 *  - all indices
                 *  - resolve indices at search time
                 *
                 * request.indices(changeCollector.getIndicesToQuery(lastCheckpoint, nextCheckpoint).toArray(new String[0]));
                 */
                request.indices(getConfig().getSource().getIndex());
            } else {
                request.indices(getConfig().getSource().getIndex());
            }
            queryBuilder = filteredQuery;
        } else {
            request.indices(getConfig().getSource().getIndex());
        }
        sourceBuilder.query(queryBuilder);
        logger.debug("[{}] Querying {} for data: {}", getJobId(), request.indices(), sourceBuilder);
        return request.source(sourceBuilder)
            .allowPartialSearchResults(false) 
            .indicesOptions(IndicesOptions.LENIENT_EXPAND_OPEN); 
    }
    /**
     * Handle the circuit breaking case: A search consumed to much memory and got aborted.
     *
     * Going out of memory we smoothly reduce the page size which reduces memory consumption.
     *
     * Implementation details: We take the values from the circuit breaker as a hint, but
     * note that it breaks early, that's why we also reduce using
     *