ES|QL: execution planner leaking temporary field name

[luigidellaquila]

With CSV dataset:

from firewall_logs,threat_list,airports 
| keep `message`, `name`, source.IP, `type`, message 
| enrich languages_policy on message 
| drop type 
| dissect name "%{message}"
| rename language_name as message 
| lookup join message_types_lookup on message 
| rename `source.IP` AS EkooZqOYHpD, `EkooZqOYHpD` AS `XzWnUOjttGQD` 
| drop `XzWnUOjttGQD` | stats  type = count_distinct(name), `name` = count(*), JhbpKFAaRq = count(*) 
| limit 5791 
| keep name 
| eval  `name` = true, nhIWDevxEtU = null, name = true, `name` = 1, sPMxyWXGSHm = "a", TewXimOwcBYr = true 
| stats  `nhIWDevxEtU` = min(name) by name 
| eval  dsjbDWegyVkg = false, name = null, name = 1, nhIWDevxEtU = null, iPIbTFddDK = 1, rUvqtgSl = 1

{
    "took": 22,
    "is_partial": false,
    "documents_found": 0,
    "values_loaded": 0,
    "columns": [
        {
            "name": "$$name$temp_name$1024",
            "type": "integer"
        },
        {
            "name": "dsjbDWegyVkg",
            "type": "boolean"
        },
        {
            "name": "name",
            "type": "integer"
        },
        {
            "name": "nhIWDevxEtU",
            "type": "null"
        },
        {
            "name": "iPIbTFddDK",
            "type": "integer"
        },
        {
            "name": "rUvqtgSl",
            "type": "integer"
        }
    ],
    "values": [
        [
            1,
            false,
            1,
            null,
            1,
            1
        ]
    ]
}

$$name$temp_name$1024 shouldn't be there

[elasticsearchmachine]

Pinging @elastic/es-analytical-engine (Team:Analytics)