add unit test coverage for KubernetesClient.generatePodName

[mengw15]

Task Summary

computing-unit-managing-service/src/main/scala/org/apache/texera/service/util/KubernetesClient.scala (0% coverage) has a pure string-building helper that needs no cluster: generatePodName(cuid). Cover it; the client-backed methods (getPodByName, getPodMetrics, createPod, …) and generatePodURI (which embeds KubernetesConfig values) need a fabric8 mock / config control and are out of scope here.

Behavior to cover

• generatePodName(42) == "computing-unit-42"
• generatePodName(0) == "computing-unit-0" (boundary)

Task Type

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