Remove accidentally backported Fork capability

Author: ChrisHegarty

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

@@ -826,11 +826,6 @@ public enum Cap {
          */
         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
          */