fix(docker): make kubectl-delivery base image and k8s version configurable

[vicoooo26]

What this PR does / why we need it:

Makes the kubectl-delivery Dockerfile more flexible by extracting hardcoded Alpine and Kubernetes versions into build args:

• ALPINE_VERSION (default 3.22) — replaces the hardcoded alpine:3.17 in both build and final stages
• K8S_VERSION (default v1.30.7) — replaces the hardcoded ENV K8S_VERSION with an ARG, allowing override via --build-arg

This also upgrades the Alpine base from 3.17 to 3.22, bringing security fixes and updated packages. Both values can now be overridden at build time without editing the Dockerfile.

[github-actions]

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