[Feature] Support `show meta-services` for cloud mode just as `show backends`

[gavinchou]

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

Description

1. add role recycler to registry key, see cloud/src/meta-service/keys.h MetaServiceRegistryPB for more info
2. support show meta-services SQL command to show current running meta-services processes just as show backends

note that: the result of show command is from the first step registry key

Use case

No response

Related issues

No response

Are you willing to submit PR?

• Yes I am willing to submit a PR!

Code of Conduct

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

[msridhar78]

@gavinchou Please assign this issue to me