Simplify testSearchWhileRelocating (#128095)

This change logs the query failure as well as stops the test immediately after it.
This makes it easier to read the logs and troubleshot the flaky failures once they happen.

Author: idegtiarenko

x-pack/plugin/esql/src/internalClusterTest/java/org/elasticsearch/xpack/esql/action/ManyShardsIT.java

@@ -122,7 +122,7 @@ public void testConcurrentQueries() throws Exception {
                     logger.warn("Query failed with exception", e);
                     throw e;
                 }
-            }, "testConcurrentQueries");
+            }, "testConcurrentQueries-" + q);
         }
         for (Thread thread : threads) {
             thread.start();

x-pack/plugin/esql/src/internalClusterTest/java/org/elasticsearch/xpack/esql/plugin/DataNodeRequestSenderIT.java

@@ -21,12 +21,10 @@
 
 import java.util.Collection;
 import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.concurrent.atomic.LongAdder;
 
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.elasticsearch.xpack.esql.EsqlTestUtils.as;
 import static org.elasticsearch.xpack.esql.EsqlTestUtils.getValuesList;
-import static org.hamcrest.Matchers.greaterThan;
 import static org.hamcrest.Matchers.hasSize;
 
 public class DataNodeRequestSenderIT extends AbstractEsqlIntegTestCase {
@@ -52,17 +50,19 @@ public void testSearchWhileRelocating() throws InterruptedException {
 
         // start background searches
         var stopped = new AtomicBoolean(false);
-        var queries = new LongAdder();
         var threads = new Thread[randomIntBetween(1, 5)];
         for (int i = 0; i < threads.length; i++) {
             threads[i] = new Thread(() -> {
                 while (stopped.get() == false) {
                     try (EsqlQueryResponse resp = run("FROM index-1")) {
                         assertThat(getValuesList(resp), hasSize(docs));
+                    } catch (Exception | AssertionError e) {
+                        logger.warn("Query failed with exception", e);
+                        stopped.set(true);
+                        throw e;
                     }
-                    queries.increment();
                 }
-            });
+            }, "testSearchWhileRelocating-" + i);
         }
         for (Thread thread : threads) {
             thread.start();
@@ -93,7 +93,6 @@ public void testSearchWhileRelocating() throws InterruptedException {
             .prepareUpdateSettings(TEST_REQUEST_TIMEOUT, TEST_REQUEST_TIMEOUT)
             .setPersistentSettings(Settings.builder().putNull("cluster.routing.allocation.exclude._name"))
             .get();
-        assertThat(queries.sum(), greaterThan((long) threads.length));
     }
 
     public void testRetryOnShardMovement() {