Fix config for metaclient

[xyuanlu]

Issues

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#2808

Description

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Config for leader election client should cover all params in metaclient config.

Tests

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  Verified manually using break point. Session timeout is buried in native ZK connection object, cant compare without modifying the ZkConnection class.

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Code Quality

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[junkaixue]

Why we don't have config validator? Or these are the optional fields.

[xyuanlu]

These are optional fields. If user do not populate, they will have default values.

[junkaixue]

this pr is fine. would be good to think of how to prevent config missing in the future.

[xyuanlu]

this change is ready to be merged. approved by @junkaixue

commit msg:
Fix config for metaclient leader election client.