always call rows.Close

[li-zhao-hotstar]

Summary

follow go convention to always close rows, irrespective of success scans or early error returns

Checklist

Delete items not relevant to your PR:

• Unit and integration tests covering the common scenarios were added
• A human-readable description of the changes was provided to include in CHANGELOG
• For significant changes, documentation in https://github.com/ClickHouse/clickhouse-docs was updated with further explanations or tutorials

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[jkaflik]

Thanks. Could you sign CLA please?