### 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
}
    protected Tuple<String, SearchRequest> buildSearchRequest() {
        assert nextCheckpoint != null;
        switch (runState) {
            case APPLY_RESULTS:
                return new Tuple<>("apply_results", buildQueryToUpdateDestinationIndex());
            case IDENTIFY_CHANGES:
                return new Tuple<>("identify_changes", buildQueryToFindChanges());
            default:
                
                logger.warn("Encountered unexpected run state [" + runState + "]");
                throw new IllegalStateException("Transform indexer job encountered an illegal state [" + runState + "]");
        }
    }
    private SearchRequest buildQueryToFindChanges() {
        assert isContinuous();
        TransformIndexerPosition position = getPosition();
        SearchSourceBuilder sourceBuilder = new SearchSourceBuilder().runtimeMappings(getConfig().getSource().getRuntimeMappings());
        
        SearchRequest request = new SearchRequest(
            /*
             * gh#77329 optimization turned off, 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
             *
             * TransformCheckpoint.getChangedIndices(TransformCheckpoint.EMPTY, getNextCheckpoint()).toArray(new String[0])
             */
            getConfig().getSource().getIndex()