Fix Flaky SearchServiceTests.testConcurrentSegmentSearchWithRandomizedModeSettings

Signed-off-by: kkewwei <kewei.11@bytedance.com>
Signed-off-by: kkewwei <kkewwei@163.com>

Author: kkewwei

server/src/test/java/org/opensearch/search/SearchServiceTests.java

@@ -1498,11 +1498,12 @@ public void testConcurrentSegmentSearchWithRandomizedModeSettings() throws IOExc
         String clusterMode = randomFrom(modeSettings);
         String indexMode = randomFrom(modeSettings);
 
-        // default to false in case mode setting is not set
-        boolean concurrentSearchEnabled = false;
-
         boolean aggregationSupportsConcurrent = randomBoolean();
 
+        // Default to auto in case mode setting is not set, we use true to represent,
+        // It is also decided by aggregationSupportsConcurrent.
+        boolean concurrentSearchEnabled = true && aggregationSupportsConcurrent;
+
         if (indexMode != null) {
             concurrentSearchEnabled = !indexMode.equals("none") && aggregationSupportsConcurrent;
         } else if (clusterMode != null) {