Unmute NativeArrayIntegrationTestCase tests (elastic#139192)

I'm unable to reproduce the failure. Somehow the test requested a field didn't exist, which caused a NPE.

Unmuting the test and adding more logging in case it fails again in CI.

Closes elastic#139153

Author: martijnvg

muted-tests.yml

@@ -415,9 +415,6 @@ tests:
 - class: org.elasticsearch.test.rest.yaml.CcsCommonYamlTestSuiteIT
   method: test {p0=scroll/20_keep_alive/Max keep alive}
   issue: https://github.com/elastic/elasticsearch/issues/138680
-- class: org.elasticsearch.xpack.unsignedlong.UnsignedLongSyntheticSourceNativeArrayIntegrationTests
-  method: testSynthesizeArrayRandom
-  issue: https://github.com/elastic/elasticsearch/issues/138684
 - class: org.elasticsearch.xpack.esql.optimizer.LocalLogicalPlanOptimizerTests
   method: testAggregateMetricDoubleInlineStats
   issue: https://github.com/elastic/elasticsearch/issues/138620
@@ -448,9 +445,9 @@ tests:
 - class: org.elasticsearch.xpack.remotecluster.CrossClusterEsqlRCS1EnrichUnavailableRemotesIT
   method: testEsqlEnrichWithSkipUnavailable
   issue: https://github.com/elastic/elasticsearch/issues/138793
-- class: org.elasticsearch.index.mapper.LongSyntheticSourceNativeArrayIntegrationTests
-  method: testSynthesizeArrayRandom
-  issue: https://github.com/elastic/elasticsearch/issues/138819
+- class: org.elasticsearch.xpack.ilm.actions.DownsampleActionIT
+  method: testILMWaitsForTimeSeriesEndTimeToLapse
+  issue: https://github.com/elastic/elasticsearch/issues/138843
 - class: org.elasticsearch.test.rest.yaml.CcsCommonYamlTestSuiteIT
   method: test {p0=search/610_function_score/formulating a function score query with a negative number returns bad request}
   issue: https://github.com/elastic/elasticsearch/issues/138908

test/framework/src/main/java/org/elasticsearch/index/mapper/NativeArrayIntegrationTestCase.java

@@ -9,6 +9,7 @@
 
 package org.elasticsearch.index.mapper;
 
+import org.apache.lucene.index.DirectoryReader;
 import org.apache.lucene.index.DocValuesType;
 import org.apache.lucene.index.FieldInfo;
 import org.apache.lucene.index.FieldInfos;
@@ -313,7 +314,9 @@ protected void verifySyntheticArray(
                 Set<String> storedFieldNames = new LinkedHashSet<>(document.getFields().stream().map(IndexableField::name).toList());
                 assertThat(storedFieldNames, contains(expectedStoredFields));
             }
-            var fieldInfo = FieldInfos.getMergedFieldInfos(reader).fieldInfo("field.offsets");
+            var fieldInfos = getFieldInfos(reader);
+            var fieldInfo = fieldInfos.fieldInfo("field.offsets");
+            assertThat(fieldInfo, notNullValue());
             assertThat(fieldInfo.getDocValuesType(), equalTo(DocValuesType.SORTED));
         }
     }
@@ -432,9 +435,18 @@ protected void verifySyntheticArrayInObject(List<Object[]> documents) throws IOE
                 Set<String> storedFieldNames = new LinkedHashSet<>(document.getFields().stream().map(IndexableField::name).toList());
                 assertThat(storedFieldNames, contains("_id"));
             }
-            var fieldInfo = FieldInfos.getMergedFieldInfos(reader).fieldInfo("object.field.offsets");
+            var fieldInfos = getFieldInfos(reader);
+            var fieldInfo = fieldInfos.fieldInfo("object.field.offsets");
+            assertThat(fieldInfo, notNullValue());
             assertThat(fieldInfo.getDocValuesType(), equalTo(DocValuesType.SORTED));
         }
     }
 
+    private FieldInfos getFieldInfos(DirectoryReader reader) {
+        var fieldInfos = FieldInfos.getMergedFieldInfos(reader);
+        for (FieldInfo fieldInfo : fieldInfos) {
+            logger.info("field name: {}, {}", fieldInfo.name, fieldInfo.attributes());
+        }
+        return fieldInfos;
+    }
 }