Flaky-test: PulsarFunctionMetadataStoreTest.setup

[example failure](https://github.com/apache/pulsar/runs/7471854928?check_suite_focus=true)

```
Error: Tests run: 21, Failures: 1, Errors: 0, Skipped: 11, Time elapsed: 142.439 s <<< FAILURE! - in org.apache.pulsar.functions.worker.PulsarFunctionMetadataStoreTest
Error: setup(org.apache.pulsar.functions.worker.PulsarFunctionMetadataStoreTest) Time elapsed: 19.964 s <<< FAILURE!
org.awaitility.core.ConditionTimeoutException: Assertion condition defined as a org.apache.pulsar.functions.worker.FileServer null within 10 seconds.
at org.awaitility.core.ConditionAwaiter.await(ConditionAwaiter.java:167)
at org.awaitility.core.AssertionCondition.await(AssertionCondition.java:119)
at org.awaitility.core.AssertionCondition.await(AssertionCondition.java:31)
at org.awaitility.core.ConditionFactory.until(ConditionFactory.java:985)
at org.awaitility.core.ConditionFactory.untilAsserted(ConditionFactory.java:769)
at org.apache.pulsar.functions.worker.FileServer.waitUntilServerIsAvailable(FileServer.java:82)
at org.apache.pulsar.functions.worker.FileServer.start(FileServer.java:72)
at org.apache.pulsar.functions.worker.PulsarFunctionLocalRunTest.setup(PulsarFunctionLocalRunTest.java:305)
at jdk.internal.reflect.GeneratedMethodAccessor958.invoke(Unknown Source)
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.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:132)
at org.testng.internal.MethodInvocationHelper.invokeMethodConsideringTimeout(MethodInvocationHelper.java:61)
at org.testng.internal.ConfigInvoker.invokeConfigurationMethod(ConfigInvoker.java:366)
at org.testng.internal.ConfigInvoker.invokeConfigurations(ConfigInvoker.java:320)
at org.testng.internal.TestInvoker.runConfigMethods(TestInvoker.java:701)
at org.testng.internal.TestInvoker.invokeMethod(TestInvoker.java:527)
at org.testng.internal.TestInvoker.invokeTestMethod(TestInvoker.java:174)
at org.testng.internal.MethodRunner.runInSequence(MethodRunner.java:46)
at org.testng.internal.TestInvoker$MethodInvocationAgent.invoke(TestInvoker.java:822)
at org.testng.internal.TestInvoker.invokeTestMethods(TestInvoker.java:147)
at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:146)
at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:128)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
at org.testng.TestRunner.privateRun(TestRunner.java:764)
at org.testng.TestRunner.run(TestRunner.java:585)
at org.testng.SuiteRunner.runTest(SuiteRunner.java:384)
at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:378)
at org.testng.SuiteRunner.privateRun(SuiteRunner.java:337)
at org.testng.SuiteRunner.run(SuiteRunner.java:286)
at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:53)
at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:96)
at org.testng.TestNG.runSuitesSequentially(TestNG.java:1218)
at org.testng.TestNG.runSuitesLocally(TestNG.java:1140)
at org.testng.TestNG.runSuites(TestNG.java:1069)
at org.testng.TestNG.run(TestNG.java:1037)
at org.apache.maven.surefire.testng.TestNGExecutor.run(TestNGExecutor.java:135)
at org.apache.maven.surefire.testng.TestNGDirectoryTestSuite.executeSingleClass(TestNGDirectoryTestSuite.java:112)
at org.apache.maven.surefire.testng.TestNGDirectoryTestSuite.executeLazy(TestNGDirectoryTestSuite.java:123)
at org.apache.maven.surefire.testng.TestNGDirectoryTestSuite.execute(TestNGDirectoryTestSuite.java:90)
at org.apache.maven.surefire.testng.TestNGProvider.invoke(TestNGProvider.java:146)
at org.apache.maven.surefire.booter.ForkedBooter.invokeProviderInSameClassLoader(ForkedBooter.java:384)
at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:345)
at org.apache.maven.surefire.booter.ForkedBooter.execute(ForkedBooter.java:126)
at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:418)
Caused by: java.util.concurrent.TimeoutException
at java.base/java.util.concurrent.FutureTask.get(FutureTask.java:204)
at org.awaitility.core.Uninterruptibles.getUninterruptibly(Uninterruptibles.java:101)
at org.awaitility.core.Uninterruptibles.getUninterruptibly(Uninterruptibles.java:81)
at org.awaitility.core.ConditionAwaiter.await(ConditionAwaiter.java:103)
... 44 more
```

Start with PulsarFunctionMetadataStoreTest.setup and the stack trace through PulsarFunctionLocalRunTest.java:305 and FileServer.java:72-82. Run the named test and investigate why FileServer does not become available within the Awaitility timeout; done means the setup no longer flakes and the test passes reliably.

Written by the indexing model from the issue text.