Looks like a leaked `Exchange`?

**Build scan:**
https://gradle-enterprise.elastic.co/s/mmrtyhckobkwo/tests/:x-pack:plugin:esql:internalClusterTest/org.elasticsearch.xpack.esql.action.EsqlActionIT/testShowFunctions

**Reproduction line:**
```
./gradlew ':x-pack:plugin:esql:internalClusterTest' --tests "org.elasticsearch.xpack.esql.action.EsqlActionIT.testShowFunctions" -Dtests.seed=8850B71504CB7FA5 -Dtests.locale=ar-EG -Dtests.timezone=Asia/Harbin -Druntime.java=21
```

**Applicable branches:**
main

**Reproduces locally?:**
Didn't try

**Failure history:**
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.xpack.esql.action.EsqlActionIT&tests.test=testShowFunctions

**Failure excerpt:**
```
java.lang.AssertionError: Leftover exchanges ExchangeService{sinks=[xDupaxgARhq3e5LBrywuWw:4601], sources=[]} on node node_s0

  at org.junit.Assert.fail(Assert.java:88)
  at org.junit.Assert.assertTrue(Assert.java:41)
  at org.elasticsearch.xpack.esql.action.AbstractEsqlIntegTestCase.lambda$ensureExchangesAreReleased$0(AbstractEsqlIntegTestCase.java:38)
  at org.elasticsearch.test.ESTestCase.assertBusy(ESTestCase.java:1196)
  at org.elasticsearch.test.ESTestCase.assertBusy(ESTestCase.java:1169)
  at org.elasticsearch.xpack.esql.action.AbstractEsqlIntegTestCase.ensureExchangesAreReleased(AbstractEsqlIntegTestCase.java:38)
  at jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
  at java.lang.reflect.Method.invoke(Method.java:580)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.invoke(RandomizedRunner.java:1758)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$10.evaluate(RandomizedRunner.java:1004)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleSetupTeardownChained$1.evaluate(TestRuleSetupTeardownChained.java:48)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.tests.util.TestRuleThreadAndTestName$1.evaluate(TestRuleThreadAndTestName.java:45)
  at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.tests.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:390)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.forkTimeoutingTask(ThreadLeakControl.java:843)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$3.evaluate(ThreadLeakControl.java:490)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.runSingleTest(RandomizedRunner.java:955)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$5.evaluate(RandomizedRunner.java:840)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$6.evaluate(RandomizedRunner.java:891)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$7.evaluate(RandomizedRunner.java:902)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleStoreClassName$1.evaluate(TestRuleStoreClassName.java:38)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleAssertionsRequired$1.evaluate(TestRuleAssertionsRequired.java:53)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.tests.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
  at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.tests.util.TestRuleIgnoreTestSuites$1.evaluate(TestRuleIgnoreTestSuites.java:47)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:390)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.lambda$forkTimeoutingTask$0(ThreadLeakControl.java:850)
  at java.lang.Thread.run(Thread.java:1583)

```
x-pack/plugin/esql/compute/src/test/java/org/elasticsearch/compute/lucene/LuceneCountOperatorTests.java
return new LuceneCountOperator.Factory(List.of(ctx), queryFunction, dataPartitioning, 1, limit);
    }
    @Override
    protected String expectedToStringOfSimple() {
        assumeFalse("can't support variable maxPageSize", true); 
        return "LuceneCountOperator[shardId=0, maxPageSize=**random**]";
    }
    @Override
    protected String expectedDescriptionOfSimple() {
        assumeFalse("can't support variable maxPageSize", true); 
        return """
            LuceneCountOperator[dataPartitioning = SHARD, maxPageSize = **random**, limit = 100, sorts = [{"s":{"order":"asc"}}]]""";
    }
    
    public void testShardDataPartitioning() {
        int size = between(1_000, 20_000);
        int limit = between(10, size);
        testCount(size, limit);
    }
    public void testEmpty() {
        testCount(0, between(10, 10_000));
    }
    private void testCount(int size, int limit) {
        DriverContext ctx = driverContext();
        LuceneCountOperator.Factory factory = simple(nonBreakingBigArrays(), DataPartitioning.SHARD, size, limit);
        List<Page> results = new ArrayList<>();
        OperatorTestCase.runDriver(new Driver(ctx, factory.get(ctx), List.of(), new PageConsumerOperator(results::add), () -> {}));
        OperatorTestCase.assertDriverContext(ctx);
        assertThat(results, hasSize(1));
        Page page = results.get(0);