Flaky testFutureCompletionOutsidePoll in ConsumerNetworkClientTest

Fails with:

org.opentest4j.AssertionFailedError: expected: <true> but was: <false> at org.junit.jupiter.api.AssertionFailureBuilder.build(AssertionFailureBuilder.java:151) at org.junit.jupiter.api.AssertionFailureBuilder.buildAndThrow(AssertionFailureBuilder.java:132) at org.junit.jupiter.api.AssertTrue.failNotTrue(AssertTrue.java:63) at org.junit.jupiter.api.AssertTrue.assertTrue(AssertTrue.java:36) at org.junit.jupiter.api.AssertTrue.assertTrue(AssertTrue.java:31) at org.junit.jupiter.api.Assertions.assertTrue(Assertions.java:183) at org.apache.kafka.clients.consumer.internals.ConsumerNetworkClientTest.testFutureCompletionOutsidePoll(ConsumerNetworkClientTest.java:295) at java.lang.reflect.Method.invoke(Method.java:498) at java.util.ArrayList.forEach(ArrayList.java:1259) at java.util.ArrayList.forEach(ArrayList.java:1259)

Flaky behaviour started recently (~ Aug 27, 2024): https://ge.apache.org/scans/tests?search.names=Git%20branch&search.rootProjectNames=kafka&search.startTimeMax=1726258207388&search.startTimeMin=1721102400000&search.timeZoneId=America%2FToronto&search.values=trunk&tests.container=org.apache.kafka.clients.consumer.internals.ConsumerNetworkClientTest&tests.test=testFutureCompletionOutsidePoll()