### Description

![image](https://github.com/elastic/elasticsearch/assets/76245/d0443170-0419-4759-b505-7620ff3d6594)

The execution time of grouping stats by multiple keywords has increased: 1.2 to 1.6 seconds (with doc_partitioning), 4.3 to 6.7 seconds (with shard_partitioning). The equivalent query with the _search API takes 1.8 seconds.

`from nyc_taxis | ... | stats c = count(dropoff_datetime) by trip_type, payment_type, vendor_id`

This regression occurred since July 2, 2023, and I suspect it may be due to the PR: [Support multivalued fields on arbitrary grouping](https://github.com/elastic/elasticsearch-internal/pull/1340).

/cc @nik9000
x-pack/plugin/esql/compute/src/test/java/org/elasticsearch/compute/operator/MultivalueDedupeTests.java
import java.util.HashSet;
import java.util.List;
import java.util.NavigableSet;
import java.util.Set;
import java.util.TreeSet;
import java.util.function.LongFunction;
import java.util.stream.Collectors;
import static org.hamcrest.Matchers.containsInAnyOrder;
import static org.hamcrest.Matchers.equalTo;
import static org.hamcrest.Matchers.greaterThan;
import static org.hamcrest.Matchers.greaterThanOrEqualTo;
import static org.hamcrest.Matchers.nullValue;
public class MultivalueDedupeTests extends ESTestCase {
    public static List<ElementType> supportedTypes() {
        List<ElementType> supported = new ArrayList<>();
        for (ElementType elementType : ElementType.values()) {
            if (elementType == ElementType.UNKNOWN || elementType == ElementType.NULL || elementType == ElementType.DOC) {
                continue;
            }
            supported.add(elementType);
        }
        return supported;
    }
    @ParametersFactory
    public static List<Object[]> params() {
        List<Object[]> params = new ArrayList<>();
        for (ElementType elementType : supportedTypes()) {
            if (elementType == ElementType.UNKNOWN || elementType == ElementType.NULL || elementType == ElementType.DOC) {
                continue;
            }