### Elasticsearch Version

main

### Installed Plugins

_No response_

### Java Version

_bundled_

### OS Version

all

### Problem Description

Do this

### Steps to Reproduce

```
rm /tmp/evil
for a in {0..9}; do
   for b in {0..9}; do
      echo '{"index": {}}' >> /tmp/evil
      echo '{"a": '$a', "b": '$b'}' >> /tmp/evil
   done
done
echo >> /tmp/evil

curl -uelastic:password -XDELETE localhost:9200/test
curl -HContent-Type:application/json -uelastic:password -XPUT localhost:9200/test
curl -HContent-Type:application/json -uelastic:password -XPOST localhost:9200/test/_bulk --data-binary @/tmp/evil
curl -HContent-Type:application/json -uelastic:password -XPOST localhost:9200/test/_forcemerge?max_num_segments=1
curl -HContent-Type:application/json -uelastic:password -XPOST localhost:9200/test/_refresh

curl -HContent-Type:application/json -uelastic:password -XPOST localhost:9200/_esql?pretty -d'{
   "query": "FROM test | STATS MAX(a) BY a, b | KEEP a"
}'
```

### Logs (if relevant)

_No response_
x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/planner/LocalExecutionPlanner.java
final List<DriverFactory> driverFactories;
        LocalExecutionPlan(List<DriverFactory> driverFactories) {
            this.driverFactories = driverFactories;
        }
        public List<Driver> createDrivers(String sessionId) {
            List<Driver> drivers = new ArrayList<>();
            for (DriverFactory df : driverFactories) {
                for (int i = 0; i < df.driverParallelism.instanceCount; i++) {
                    drivers.add(df.driverSupplier.apply(sessionId));
                }
            }
            return drivers;
        }
        @Override
        public String describe() {
            StringBuilder sb = new StringBuilder();
            sb.append(driverFactories.stream().map(DriverFactory::describe).collect(joining("\n")));
            return sb.toString();
        }
    }
}