Fix testMaxQueueLatency bug (elastic#131112)

Cannot expect thread pool task to have
completed because the test only asserts
that the task has started execution

Closes elastic#131093

Author: DiannaHohensee

muted-tests.yml

@@ -520,9 +520,6 @@ tests:
 - class: org.elasticsearch.xpack.esql.action.EsqlActionBreakerIT
   method: testRowStatsProjectGroupByInt
   issue: https://github.com/elastic/elasticsearch/issues/131024
-- class: org.elasticsearch.common.util.concurrent.TaskExecutionTimeTrackingEsThreadPoolExecutorTests
-  method: testMaxQueueLatency
-  issue: https://github.com/elastic/elasticsearch/issues/131093
 - class: org.elasticsearch.xpack.esql.action.CrossClusterAsyncQueryStopIT
   method: testStopQueryLocal
   issue: https://github.com/elastic/elasticsearch/issues/121672

server/src/test/java/org/elasticsearch/common/util/concurrent/TaskExecutionTimeTrackingEsThreadPoolExecutorTests.java

@@ -146,7 +146,6 @@ public void testMaxQueueLatency() throws Exception {
             assertEquals("The max was just reset, should be zero", 0, executor.getMaxQueueLatencyMillisSinceLastPollAndReset());
         } finally {
             // Clean up.
-            assertThat(executor.getOngoingTasks().toString(), executor.getOngoingTasks().size(), equalTo(0));
             executor.shutdown();
             executor.awaitTermination(10, TimeUnit.SECONDS);
         }