
Filing this issue to track a question/comment that was raised by @ywangd  here https://github.com/elastic/elasticsearch/pull/98309#discussion_r1294115440

One question I do have is why we chose to [execute the LookupRequest with the enrich origin](https://github.com/elastic/elasticsearch/blob/2e4440ff1c0decf79f8a40688566411f7d518aa7/x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/enrich/EnrichLookupService.java#L141C2-L141C2). It means the following query works when the user has access to only the playlist index without access to either the songs enrich policy or its associated index.

```
FROM playlist | ENRICH songs ON song_id
```

It feels a bit weird to me that we have no control on who can use what enrich process. That said, we don't have a good story around enrich and ingest pipeline either, i.e. we have no control over who can use what pipeline where a pipeline can contain an enrich processor. There have been quite a few complaints from users and we have an https://github.com/elastic/elasticsearch/issues/57586 for it. I wonder whether we should not repeat the problem here with ES|QL. On the surface, it might be easier to tackle compared to ingest pipelines since ES|QL is read-only and has no "bulk" operations. What do you think?
x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/optimizer/LogicalPlanOptimizer.java
@Override
        protected LogicalPlan rule(Enrich re) {
            LogicalPlan child = re.child();
            if (child instanceof OrderBy orderBy) {
                return orderBy.replaceChild(re.replaceChild(orderBy.child()));
            } else if (child instanceof Project) {
                var projectWithChild = pushDownPastProject(re);
                var attrs = asAttributes(re.enrichFields());
                return projectWithChild.withProjections(mergeOutputExpressions(attrs, projectWithChild.projections()));
            }
            return re;
        }
    }
    protected static class PushDownAndCombineOrderBy extends OptimizerRules.OptimizerRule<OrderBy> {
        @Override
        protected LogicalPlan rule(OrderBy orderBy) {
            LogicalPlan child = orderBy.child();
            if (child instanceof OrderBy childOrder) {
                
                return new OrderBy(orderBy.source(), childOrder.child(), CollectionUtils.combine(orderBy.order(), childOrder.order()));
            } else if (child instanceof Project) {
                return pushDownPastProject(orderBy);
            }
            return orderBy;
        }
    }
    /**
     * Remove unused columns created in the plan, in fields inside eval or aggregations inside stats.
     */
    static class PruneColumns extends Rule<LogicalPlan, LogicalPlan> {