Add InitContainer Support in Charts

<!-- Please answer these questions before submitting your feature request. Thanks! --> **Is your feature request related to a problem? Please describe.** Currently, the descheduler Helm chart does not support adding init containers to the pod spec. This limitation prevents users from running initialization tasks before the descheduler container starts, such as: - Pre-loading configuration from external sources - Waiting for dependencies to be ready - Setting up required files or permissions - Running security scans or compliance checks **Describe the solution you'd like** Add support for initContainers in the Helm chart's values.yaml file, similar to how other Kubernetes Helm charts handle init containers. Users should be able to define init containers in their values file **Describe alternatives you've considered** Forking the chart and maintaining a custom version (not ideal for maintenance) Using Kustomize overlays to patch the deployment/cronjob (adds complexity) Running init tasks as separate Jobs before deploying descheduler (doesn't guarantee execution order) **What version of descheduler are you using?** descheduler version: descheduler version: v0.34.0 (chart version 0.34.0) **Additional context** <!-- Add any other context or screenshots about the feature request here. -->