add unit test coverage for ComputingUnitSelectionComponent

[mengw15]

Task Summary

frontend/src/app/workspace/component/power-button/computing-unit-selection.component.ts (codecov ~59%) has a spec (prior coverage in #6347 / #5538, both closed) but ~29 methods remain untested — mostly pure resource-display getters. Extend it. See frontend/TESTING.md.

Behavior to add

• pure resource getters (deterministic, easy wins): the getCpu* / getMemory* / getGpuLimit / getJvmMemorySize / getSharedMemorySize / getBadgeColor / get*Status / get*Percentage / get*Unit / get*Value family — assert output for sample unit inputs
• getCurrentComputingUnit* accessors (cpu / memory / gpu limits + usage)
• trackByCuid / trackByIndex — trackBy identity
• cancelEditingUnitName / getUnitStatusTooltip / openComputingUnitMetadataModal / scrollToBottomOfPipModal

Task Type

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