Descheduler code refactorings

Refactoring the code to improve readability and maintainability by simplifying logic, clarifying names, organizing structure, and ensuring consistent style—without changing existing functionality. TestPodLifeTime: - https://github.com/kubernetes-sigs/descheduler/pull/1781 - https://github.com/kubernetes-sigs/descheduler/pull/1782 - https://github.com/kubernetes-sigs/descheduler/pull/1783 - https://github.com/kubernetes-sigs/descheduler/pull/1784 - https://github.com/kubernetes-sigs/descheduler/pull/1785 - https://github.com/kubernetes-sigs/descheduler/pull/1787 - https://github.com/kubernetes-sigs/descheduler/pull/1789 - https://github.com/kubernetes-sigs/descheduler/pull/1790 TestFindDuplicatePods: - https://github.com/kubernetes-sigs/descheduler/pull/1791 - https://github.com/kubernetes-sigs/descheduler/pull/1792 - https://github.com/kubernetes-sigs/descheduler/pull/1793 TestRemovePodsHavingTooManyRestarts: - https://github.com/kubernetes-sigs/descheduler/pull/1794 TestPodAntiAffinity: - https://github.com/kubernetes-sigs/descheduler/pull/1795 TestRemovePodsViolatingNodeAffinity: - https://github.com/kubernetes-sigs/descheduler/pull/1796 TestDeletePodsViolatingNodeTaints: - https://github.com/kubernetes-sigs/descheduler/pull/1797