Refactor RandomizedRollingUpgradeIT (elastic#139572)

This PR updates the randomized rolling upgrade test to create multiple
indices with different mappings before upgrading.

In the original implementation, only the first test index was actually
being upgraded, since the test would execute sequentially for each
index. By the time the test reached the second index, the whole cluster
had already been upgraded.

Author: jordan-powers

x-pack/plugin/logsdb/qa/rolling-upgrade/src/javaRestTest/java/org/elasticsearch/xpack/logsdb/RandomizedRollingUpgradeIT.java

@@ -103,35 +103,46 @@ protected Object extendedDocValuesParams() {
         mappingGenerator = new MappingGenerator(specification);
     }
 
-    private void testIndexing(String indexName, Settings.Builder settings) throws IOException {
+    private TestIndexConfig createIndex(String indexName, Settings.Builder settings) throws IOException {
         var template = templateGenerator.generate();
         TestIndexConfig indexConfig = new TestIndexConfig(indexName, template, settings, mappingGenerator.generate(template));
 
         @SuppressWarnings("unchecked")
         Map<String, Object> mappingRaw = (Map<String, Object>) indexConfig.mapping.raw().get("_doc");
         String mappingStr = Strings.toString(XContentFactory.jsonBuilder().map(mappingRaw));
-        logger.info(indexName + " mappings: " + mappingStr);
+        logger.info(() -> indexName + " mappings: " + mappingStr);
         createIndex(indexName, settings.build(), mappingStr);
 
+        return indexConfig;
+    }
+
+    private void indexAndQueryDocuments(TestIndexConfig indexConfig) throws IOException {
         indexDocuments(indexConfig);
         testQueryAll(indexConfig);
         testEsqlSource(indexConfig);
+    }
+
+    private void testIndexing(String indexNameBase, Settings.Builder settings) throws IOException {
+        TestIndexConfig[] indexConfigs = new TestIndexConfig[NUM_INDICES];
+
+        for (int i = 0; i < NUM_INDICES; i++) {
+            indexConfigs[i] = createIndex(indexNameBase + i, settings);
+            indexAndQueryDocuments(indexConfigs[i]);
+        }
 
         int numNodes = Integer.parseInt(System.getProperty("tests.num_nodes", "3"));
         for (int i = 0; i < numNodes; i++) {
             upgradeNode(i);
-            indexDocuments(indexConfig);
-            testQueryAll(indexConfig);
-            testEsqlSource(indexConfig);
+            for (int j = 0; j < NUM_INDICES; j++) {
+                indexAndQueryDocuments(indexConfigs[j]);
+            }
         }
     }
 
     public void testIndexingStandardSource() throws IOException {
         Settings.Builder builder = Settings.builder().put(IndexSettings.INDEX_MAPPER_SOURCE_MODE_SETTING.getKey(), "stored");
         String indexNameBase = "test-index-standard-";
-        for (int i = 0; i < NUM_INDICES; i++) {
-            testIndexing(indexNameBase + i, builder);
-        }
+        testIndexing(indexNameBase, builder);
     }
 
     public void testIndexingSyntheticSource() throws IOException {
@@ -140,9 +151,7 @@ public void testIndexingSyntheticSource() throws IOException {
             builder.put(Mapper.SYNTHETIC_SOURCE_KEEP_INDEX_SETTING.getKey(), "arrays");
         }
         String indexNameBase = "test-index-synthetic-";
-        for (int i = 0; i < NUM_INDICES; i++) {
-            testIndexing(indexNameBase + i, builder);
-        }
+        testIndexing(indexNameBase, builder);
     }
 
     private void indexDocuments(TestIndexConfig indexConfig) throws IOException {