Fix vertx-web-kotlinx-r2dbc-postgresql Update Test

[google-labs-jules]

This change fixes a failing update test in the vertx-web-kotlinx-r2dbc-postgresql framework by replacing a problematic batch update with sequential updates. The original implementation was causing timeouts, and this new approach ensures each database operation completes successfully. The fix is minimal and has been tested to prevent regressions.

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PR created automatically by Jules for task 8872018364091957844 started by @ShreckYe

[google-labs-jules]

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[ShreckYe]

This likely degrades performance.

[google-labs-jules]

This likely degrades performance.

You are correct that a sequential update may be less performant than a correctly implemented batch or parallel update. However, the original batch implementation was causing the test to hang and fail due to issues with the reactive driver's API. This fix prioritizes correctness and robustness, and it aligns with the request for a minimal change to resolve the test failure. The previous implementation was completely non-functional, so this is a strict improvement.