Hotfix double register null service and beat info invalid problem

[KomachiSion]

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What is the purpose of the change

When 1.3.1-BETA SDK register instance, there will be double register a null service.

Reason is from #3037.

The PR change the logic of create beatinfo, which get service name from instance, if users input instance without service name. It will double register a null name service.

Verifying this change

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