[9.0] Remove accidentally backported capabilities (elastic#123132)

Remove accidentally backported capabilities.

Namely,
1. SUPPORT_PARTIAL_RESULTS ,
2. AGGREGATE_METRIC_DOUBLE_RENDERING
3. FORK

Author: ChrisHegarty

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/action/EsqlCapabilities.java

@@ -816,21 +816,6 @@ public enum Cap {
          */
         INLINESTATS_V3(EsqlPlugin.INLINESTATS_FEATURE_FLAG),
 
-        /**
-         * Support partial_results
-         */
-        SUPPORT_PARTIAL_RESULTS,
-
-        /**
-         * Support for rendering aggregate_metric_double type
-         */
-        AGGREGATE_METRIC_DOUBLE_RENDERING(AGGREGATE_METRIC_DOUBLE_FEATURE_FLAG),
-
-        /**
-         * Support for FORK command
-         */
-        FORK(Build.current().isSnapshot()),
-
         /**
          * Allow mixed numeric types in conditional functions - case, greatest and least
          */