[DISCUSS]Cherry-pick PIP-422 into branch-40.

[yubiao]

Hi all


I want to cherry-pick PIP-422 into branch-4.0. PIP-422 introduced the following 
two commands to help topic deletion , which is very useful when enabled a 
Geo-Replication with globak metadta store


```

pulsar-admin topicPolicies --set-replication-cluster <clusters> --global <topic>

pulsar-admin topicPolicies delete <topic>

```


Thanks
Yubiao Feng