CI: Replace unmaintained redhat-actions (buildah-build, push-to-registry, oc-login)

[ctron]

Summary

Several redhat-actions used in CI target Node.js 20, which is deprecated by GitHub Actions. All three actions are unmaintained — no new releases since early 2024, and no Node 24 update is forthcoming.

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24:
  redhat-actions/buildah-build@v2, redhat-actions/push-to-registry@v2.

Reference: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Jira: TC-5166

Actions to replace

Action	Last release	Used in
redhat-actions/buildah-build@v2	v2.13, Mar 2024	.github/actions/build-container/action.yaml (3 uses)
redhat-actions/push-to-registry@v2	v2.8, Mar 2024	.github/workflows/release.yaml (3 uses), .github/workflows/latest-release.yaml (3 uses)
redhat-actions/oc-login@v1	v1.3, Mar 2024	.github/workflows/latest-release.yaml (1 use — deploy job)

Possible replacements

• buildah-build: use docker/build-push-action or raw buildah CLI steps
• push-to-registry: use docker/login-action + docker/build-push-action, or raw podman push / buildah push CLI steps
• oc-login: use a raw oc login CLI step (the action is a thin wrapper around the CLI anyway)

[ctron]

Jira: TC-5166