Simplify ESQL specific operations using new ESQL runner (#484)

* Simplify ESQL specific operations using new ESQL runner

* Removed new stats_enrich queries that take long and cause timeouts

The only new query remaining is esql_stats_enrich_control which runs as fast as all previous enrich queries, presumably because it groups by an existing indexed field.
All the rest of the stats_enrich queries group by an enriched field, which presumably prevents some kind of optimization from being used, because they take literally 100x the time to execute.

Locally the control take about 30ms, while the others take between 3s and 9s.

nyc_taxis/challenges/default.json

@@ -1111,55 +1111,6 @@
           "clients": 1,
           "warmup-iterations": 10,
           "iterations": 50
-        },
-        {
-          "operation": "esql_stats_enrich_1",
-          "tags": ["enrich","stats"],
-          "clients": 1,
-          "warmup-iterations": 2,
-          "iterations": 5
-        },
-        {
-          "operation": "esql_stats_enrich_2",
-          "tags": ["enrich","stats"],
-          "clients": 1,
-          "warmup-iterations": 2,
-          "iterations": 5
-        },
-        {
-          "operation": "esql_stats_enrich_3",
-          "tags": ["enrich","stats"],
-          "clients": 1,
-          "warmup-iterations": 2,
-          "iterations": 5
-        },
-        {
-          "operation": "esql_stats_enrich_4",
-          "tags": ["enrich","stats"],
-          "clients": 1,
-          "warmup-iterations": 2,
-          "iterations": 5
-        },
-        {
-          "operation": "esql_stats_enrich_rates_fares",
-          "tags": ["enrich","stats"],
-          "clients": 1,
-          "warmup-iterations": 2,
-          "iterations": 5
-        },
-        {
-          "operation": "esql_stats_enrich_payments",
-          "tags": ["enrich","stats"],
-          "clients": 1,
-          "warmup-iterations": 2,
-          "iterations": 5
-        },
-        {
-          "operation": "esql_stats_enrich_payments_fares",
-          "tags": ["enrich","stats"],
-          "clients": 1,
-          "warmup-iterations": 2,
-          "iterations": 5
         }
       ]
     },