[Improvement][master] Optimize failover

[huagetai]

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• I had searched in the issues and found no similar feature requirement.

Description

Now Master server failover is mainly implemented by MasterRegistryClient and FailoverExecuteThread。Consider whether the failover code can be isolated。
This makes the responsibilities clearer：
MasterRegistryClient--Responsible for node registration、state listener、 removing dead server
FailoverExecuteThread--Responsible for executing failover
FailoverService--Responsible for failover

Use case

The function of the refactored class is clearer

Related issues

No response

Are you willing to submit a PR?

• Yes I am willing to submit a PR!

Code of Conduct

• I agree to follow this project's Code of Conduct

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