[Doc] controlled-failover Optimize example code

[zhuhai1221]

Search before asking

• I searched in the issues and found nothing similar.

What issue do you find in Pulsar docs?

https://pulsar.apache.org/docs/3.0.x/client-libraries-cluster-level-failover/#controlled-failover
There is unnecessary code present

because org.apache.pulsar.client.impl.ClientBuilderImpl#build already initialize

What is your suggestion?

delete provider.initialize(pulsarClient);


Any reference?

No response

Are you willing to submit a PR?

• I'm willing to submit a PR!

[visxu]

Yes, I checked the doc and source code, I agree the suggestion.
Please assign the issue to me.
@crossoverJie