CleanUnusedTopicCommand performs wrong

[ChaosYjh]

BUG REPORT

1. Please describe the issue you observed:

• What did you do (The steps to reproduce)?
  I found an error in org.apache.rocketmq.tools.command.broker.CleanUnusedTopicCommand when I was using cleanUnusedTopic command.

The parameter I used was '-c(clusterName)',but an error happened named "connect to {clusterName}". I found the command calls incorrect method in source code CleanUnusedTopicCommand#execute line 69.It should call defaultMQAdminExt.cleanUnusedTopic(String cluster) I think.

And In DefaultMQAdminExt#cleanUnusedTopic,there is a bad call too.It should call defaultMQAdminExtImpl#cleanUnusedTopic(String cluster) as well

2. Please tell us about your environment: rocketmq4.5.1-release