Support ignore_above for keywords in test data generation (#119416)

Author: lkts

test/framework/src/main/java/org/elasticsearch/logsdb/datageneration/datasource/DefaultMappingParametersHandler.java

@@ -65,6 +65,10 @@ private Supplier<Map<String, Object>> keywordMapping(
                 }
             }
 
+            if (ESTestCase.randomDouble() <= 0.2) {
+                injected.put("ignore_above", ESTestCase.randomIntBetween(1, 10000));
+            }
+
             return injected;
         };
     }