fix(objectql,spec)!: a groupBy on a multi-value field and a count_distinct on a JSON-stored field are refused INVALID_FIELD / 400 at the engine aggregate door, on every driver (#20808)

fix(objectql,spec)!: a groupBy on a multi-value field and a count_distinct on a JSON-stored field are refused INVALID_FIELD / 400 at the engine aggregate door, on every driver (#20808) #15483