[improve][broker] Refactor method BrokerService#unloadServiceUnit

[mattisonchao]

Motivation

Refactor method BrokerService#unloadServiceUnit to improve exception handling, logging and method call.

Modifications

• Add parameters NPE check
• Ignore the exception of topicCreationFuture

We should ignore the exception from topic creation future. It will give the caller a precise exception related to topic closing.

• throw TimeoutException when the method running timeout.

As a public method, we should let users decide what they want to do when the method runs timeout. Plus, I checked all the usage of this method and all of them ignore the exception directly. It shouldn't be a breaking change.

Verifying this change

• Make sure that the change passes the CI checks.

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete