Flaky-test: Failed to get tenant admin data for tenant public

There’s a common problem in tests which make them flaky “Failed to get tenant admin data for tenant public” happens when creating a namespace.

example failure

2022-05-18T06:44:24,018 - INFO  - [docker-java-stream--110056506:DockerUtils$2@252] - DOCKER.exec(ReaderMessagingTest-cpgsi-pulsar-broker-1:/pulsar/bin/pulsar-admin namespaces create public/ns-ivorhkkv --clusters ReaderMessagingTest-cpgsi): STDOUT: 2022-05-18T06:44:24,012+0000 [AsyncHttpClient-7-1] WARN  org.apache.pulsar.client.admin.internal.BaseResource - [http://localhost:8080/admin/v2/namespaces/public/ns-ivorhkkv] Failed to perform http put request: javax.ws.rs.InternalServerErrorException: HTTP 500 Failed to get data from /admin/policies/public
  2022-05-18T06:44:24,079 - INFO  - [docker-java-stream--110056506:DockerUtils$2@252] - DOCKER.exec(ReaderMessagingTest-cpgsi-pulsar-broker-1:/pulsar/bin/pulsar-admin namespaces create public/ns-ivorhkkv --clusters ReaderMessagingTest-cpgsi): STDERR: --- An unexpected error occurred in the server ---
  
  Message: Failed to get data from /admin/policies/public
  
  Stacktrace:
  
  org.apache.pulsar.metadata.api.MetadataStoreException: Failed to get data from /admin/policies/public
  	at org.apache.pulsar.broker.resources.BaseResources.get(BaseResources.java:88)
  	at org.apache.pulsar.broker.resources.TenantResources.getTenant(TenantResources.java:62)
  	at org.apache.pulsar.broker.web.PulsarWebResource.validateClusterForTenant(PulsarWebResource.java:401)
  	at org.apache.pulsar.broker.admin.impl.NamespacesBase.lambda$validatePolicies$89(NamespacesBase.java:2068)
  	at java.base/java.lang.Iterable.forEach(Iterable.java:75)
  	at org.apache.pulsar.broker.admin.impl.NamespacesBase.validatePolicies(NamespacesBase.java:2068)
  	at org.apache.pulsar.broker.admin.impl.NamespacesBase.lambda$internalCreateNamespace$3(NamespacesBase.java:136)
  	at java.base/java.util.concurrent.CompletableFuture$UniAccept.tryFire(CompletableFuture.java:718)
  	at java.base/java.util.concurrent.CompletableF
  2022-05-18T06:44:24,079 - INFO  - [docker-java-stream--110056506:DockerUtils$2@252] - DOCKER.exec(ReaderMessagingTest-cpgsi-pulsar-broker-1:/pulsar/bin/pulsar-admin namespaces create public/ns-ivorhkkv --clusters ReaderMessagingTest-cpgsi): STDERR: uture.postComplete(CompletableFuture.java:510)
  	at java.base/java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:2147)
  	at org.apache.pulsar.metadata.impl.ZKMetadataStore.lambda$existsFromStore$8(ZKMetadataStore.java:315)
  	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539)
  	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
  	at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304)
  	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
  	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
  	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
  	at java.base/java.lang.Thread.run(Thread.java:833)
  Caused by: java.util.concurrent.TimeoutException
  	at java.base/java.util.concurrent.CompletableFuture.timedGet(CompletableFuture.java:1960)
  	at java.base/java.util.concurr

[Technoboy-]

Make a fix here https://github.com/apache/pulsar/pull/15605/commits/d2c0fc8360cbdf247921d540a1ee2dc64b6bcfe9

[Technoboy-]

Yes, this is related to https://github.com/apache/pulsar/pull/15518. There is one place to call sync method in the createNamespace. I will fix it later. Thanks @lhotari for helping creating this issue.