BanyanDB: fix query getInstance by instance ID.

[wankai123]

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[Copilot]

Pull Request Overview

This PR fixes a bug in the BanyanDB metadata query implementation where getInstance was incorrectly querying by service ID and instance name instead of directly using the instance ID.

Key changes:

• Modified the getInstance method to query using the instance ID directly
• Removed unnecessary ID analysis logic that was decomposing the instance ID

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