Make Metadata ZKSessionTest less Flaky

[eolivelli]

Motivation

I saw these flaky tests failing on CI (private DataStax) and I believe they can be improved

[ERROR] Tests run: 6, Failures: 2, Errors: 0, Skipped: 2, Time elapsed: 48.226 s <<< FAILURE! - in org.apache.pulsar.metadata.ZKSessionTest
[ERROR] testDisconnection(org.apache.pulsar.metadata.ZKSessionTest)  Time elapsed: 10.251 s  <<< FAILURE!
java.lang.AssertionError: expected [Reconnected] but found [null]
	at org.testng.Assert.fail(Assert.java:99)
	at org.testng.Assert.failNotEquals(Assert.java:1037)
	at org.testng.Assert.assertEqualsImpl(Assert.java:140)
	at org.testng.Assert.assertEquals(Assert.java:122)
	at org.testng.Assert.assertEquals(Assert.java:617)
	at org.apache.pulsar.metadata.ZKSessionTest.testDisconnection(ZKSessionTest.java:65)
	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)

[ERROR] testReacquireLeadershipAfterSessionLost(org.apache.pulsar.metadata.ZKSessionTest)  Time elapsed: 2.475 s  <<< FAILURE!
java.lang.AssertionError: expected [Leading] but found [NoLeader]
	at org.testng.Assert.fail(Assert.java:99)
	at org.testng.Assert.failNotEquals(Assert.java:1037)
	at org.testng.Assert.assertEqualsImpl(Assert.java:140)
	at org.testng.Assert.assertEquals(Assert.java:122)
	at org.testng.Assert.assertEquals(Assert.java:617)
	at org.apache.pulsar.metadata.ZKSessionTest.testReacquireLeadershipAfterSessionLost(ZKSessionTest.java:174)
	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)

Modifications

Use Awaitility and a bigger timeout in order to make the tests less flaky

Verifying this change

This change is a trivial rework / code cleanup without any test coverage.

[lhotari]

This test remains flaky. Issue reported as #11032 .