Add a ComputingUnitMaster boot smoke test in amber-integration

[mengw15]

Task Summary

Add a boot smoke test for ComputingUnitMaster to the amber-integration job, mirroring the texera-web boot test added in #6319 (and the platform-service boot tests in #6274). Suggested by @Yicong-Huang in the #6319 review.

ComputingUnitMaster is the other server built from the amber dist (bin/computing-unit-master, port 8085); like texera-web it compiles and unit-tests clean but a runtime classpath/linkage regression (the #6204 class of bug) would only surface when its packaged launcher is actually started — which nothing in CI does today.

Current state

• ci: add a texera-web boot smoke test in amber-integration #6319 boots bin/texera-web-application (port 8080) in amber-integration via .github/scripts/smoke-boot.sh, building the amber dist in-job (ubuntu-only, no artifact hand-off).
• bin/computing-unit-master is produced by the same WorkflowExecutionService/dist but is not booted anywhere in CI.

Suggested direction

Add one more boot step in amber-integration, reusing the amber dist that #6319 already builds and unzips:

- name: Smoke-test computing-unit-master boots
  if: matrix.os == 'ubuntu-latest'
  run: .github/scripts/smoke-boot.sh "/tmp/dists/amber-*/bin/computing-unit-master" 8085

It boots on postgres only, which amber-integration already provisions — verified against ComputingUnitMaster.main/run:

• clusterMode defaults to false (no --cluster arg), so AmberRuntime.startActorMaster(false) binds a local Pekko actor system on localhost:2552 and self-seeds a single-node cluster — no external infra, and the external getNodeIpAddress call (checkip.amazonaws.com) is only reached in cluster mode.
• ApplicationConfig.cleanupAllExecutionResults defaults to false (asserted in ApplicationConfigSpec), so the boot-time result-storage cleanup (which would touch the iceberg/S3 result store) is skipped.
• The recurring expired-result check is scheduled 2s post-boot but finds no executions in the fresh (empty) texera_db, so it does no result-storage work.
• Config resolves the same way as texera-web — Utils.amberHomePath (a working-dir search for amber) → amber/src/main/resources/computing-unit-master-config.yml.

Task Type

• Refactor / Cleanup
• DevOps / Deployment / CI
• Testing / QA
• Documentation
• Performance
• Other

[github-actions]

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