fix-buildkite-ci

Triage and fix failing Buildkite CI checks for RisingWave pull requests by extracting concrete failing tests, diffs, and error messages from Buildkite build/job logs and artifacts, then applying focused code or test fixes. Use when users ask to diagnose red Buildkite checks, investigate flaky/failing CI jobs, understand why a Buildkite build failed, or provide Buildkite/GitHub check URLs and want a concrete fix.