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/src/internalClusterTest/java/org/elasticsearch/xpack/esql/action/EsqlActionIT.java
.add(new IndexRequest("test_overlapping_index_patterns_1").id("1").source("field", 10))
            .get();
        assertAcked(
            client().admin()
                .indices()
                .prepareCreate("test_overlapping_index_patterns_2")
                .setSettings(Settings.builder().put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, between(1, 5)))
                .setMapping("field", "type=keyword")
                .get()
        );
        ensureYellow("test_overlapping_index_patterns_2");
        client().prepareBulk()
            .setRefreshPolicy(WriteRequest.RefreshPolicy.IMMEDIATE)
            .add(new IndexRequest("test_overlapping_index_patterns_2").id("1").source("field", "foo"))
            .get();
        expectThrows(VerificationException.class, () -> run("from test_overlapping_index_patterns_* | sort field"));
    }
    public void testEmptyIndex() {
        assertAcked(client().admin().indices().prepareCreate("test_empty").setMapping("k", "type=keyword", "v", "type=long").get());
        EsqlQueryResponse results = run("from test_empty");
        assertThat(results.columns(), equalTo(List.of(new ColumnInfo("k", "keyword"), new ColumnInfo("v", "long"))));
        assertThat(getValuesList(results), empty());
    }
    public void testShowInfo() {
        EsqlQueryResponse results = run("show info");
        assertThat(
            results.columns(),
            equalTo(List.of(new ColumnInfo("version", "keyword"), new ColumnInfo("date", "keyword"), new ColumnInfo("hash", "keyword")))
        );
        assertThat(getValuesList(results).size(), equalTo(1));