Flaky-test: testConsumeTxnMessage

[gaozhangmin]

https://github.com/apache/pulsar/runs/5151178465?check_suite_focus=true

Error:  testConsumeTxnMessage(org.apache.pulsar.testclient.PerformanceTransactionTest)  Time elapsed: 1.248 s  <<< FAILURE!
java.lang.AssertionError: expected [null] but found [org.apache.pulsar.client.impl.MessageImpl@59e073f3]
	at org.testng.Assert.fail(Assert.java:99)
	at org.testng.Assert.failNotSame(Assert.java:1033)
	at org.testng.Assert.assertNull(Assert.java:965)
	at org.testng.Assert.assertNull(Assert.java:953)
	at org.apache.pulsar.testclient.PerformanceTransactionTest.testConsumeTxnMessage(PerformanceTransactionTest.java:235)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:132)
	at org.testng.internal.InvokeMethodRunnable.runOne(InvokeMethodRunnable.java:45)
	at org.testng.internal.InvokeMethodRunnable.call(InvokeMethodRunnable.java:73)
	at org.testng.internal.InvokeMethodRunnable.call(InvokeMethodRunnable.java:11)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:829)