Flaky-test: SimpleProducerConsumerTest.testMultiTopicsConsumerImplPauseForManualSubscription

### Search before asking

- [X] I searched in the [issues](https://github.com/apache/pulsar/issues) and found nothing similar.

### Example failure

https://github.com/apache/pulsar/actions/runs/5140514539/jobs/9252318146?pr=20267#step:10:1498

### Exception stacktrace

```

Error: Tests run: 281, Failures: 2, Errors: 0, Skipped: 221, Time elapsed: 376.068 s <<< FAILURE! - in org.apache.pulsar.client.api.SimpleProducerConsumerTest
Error: org.apache.pulsar.client.api.SimpleProducerConsumerTest.testMultiTopicsConsumerImplPauseForManualSubscription Time elapsed: 10.597 s <<< FAILURE!
java.lang.AssertionError: expected [30] but found [29]
at org.testng.Assert.fail(Assert.java:110)
at org.testng.Assert.failNotEquals(Assert.java:1577)
at org.testng.Assert.assertEqualsImpl(Assert.java:149)
at org.testng.Assert.assertEquals(Assert.java:131)
at org.testng.Assert.assertEquals(Assert.java:1418)
at org.testng.Assert.assertEquals(Assert.java:1382)
at org.testng.Assert.assertEquals(Assert.java:1428)
at org.apache.pulsar.client.api.SimpleProducerConsumerTest.testMultiTopicsConsumerImplPauseForManualSubscription(SimpleProducerConsumerTest.java:3535)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at org.testng.internal.invokers.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:139)
at org.testng.internal.invokers.InvokeMethodRunnable.runOne(InvokeMethodRunnable.java:47)
at org.testng.internal.invokers.InvokeMethodRunnable.call(InvokeMethodRunnable.java:76)
at org.testng.internal.invokers.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:1136)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at java.base/java.lang.Thread.run(Thread.java:833)
```

### Are you willing to submit a PR?

- [ ] I'm willing to submit a PR!

Start with org.apache.pulsar.client.api.SimpleProducerConsumerTest.testMultiTopicsConsumerImplPauseForManualSubscription, which fails at line 3535 with 29 messages instead of 30. Reproduce the failure using the linked GitHub Actions run and inspect the test's pause and manual-subscription behavior. Done means the test reliably passes with the expected message count.

Written by the indexing model from the issue text.