
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/ql/src/main/java/org/elasticsearch/xpack/ql/expression/AttributeMap.java
@Override
    public void clear() {
        throw new UnsupportedOperationException();
    }
    @Override
    public Set<Attribute> keySet() {
        if (keySet == null) {
            keySet = new UnwrappingSet<>(delegate.keySet()) {
                @Override
                protected Attribute unwrap(AttributeWrapper next) {
                    return next.attr;
                }
            };
        }
        return keySet;
    }
    @Override
    public Collection<E> values() {
        if (values == null) {
            values = unmodifiableCollection(delegate.values());
        }
        return values;
    }
    @Override
    public Set<Entry<Attribute, E>> entrySet() {
        if (entrySet == null) {
            entrySet = new UnwrappingSet<>(delegate.entrySet()) {
                @Override
                protected Entry<Attribute, E> unwrap(final Entry<AttributeWrapper, E> next) {
                    return new Entry<>() {