Migrate from deprecated redhat-actions/oc-installer to openshift-tools-installer

`redhat-actions/oc-installer` has been deprecated in favor of [`redhat-actions/openshift-tools-installer`](https://github.com/redhat-actions/openshift-tools-installer).

This repo has one or more GitHub Actions workflows that reference `redhat-actions/oc-installer`. While existing workflows will continue to work, the action now emits a deprecation warning and will no longer receive updates. The download mirror it points to has not been updated since December 2020.

### Migration

Replace:

```yaml
- uses: redhat-actions/oc-installer@v1
with:
oc_version: '4.6'
```

With:

```yaml
- uses: redhat-actions/openshift-tools-installer@v2
with:
oc: '4'
```

### Why migrate?

- **Semver ranges** — pin `4` instead of an exact version
- **18+ tools** — install `oc`, `helm`, `kn`, `tkn`, `yq`, and more in a single step
- **arm64 support** — works on Apple Silicon and ARM runners
- **Cross-workflow caching** — faster CI runs
- **Active maintenance** — Node 24 runtime, current dependencies

See the [openshift-tools-installer README](https://github.com/redhat-actions/openshift-tools-installer#readme) for full documentation.

Search the GitHub Actions workflow files for references to redhat-actions/oc-installer. Update each occurrence according to the migration example, then run the affected workflows and confirm that the deprecated-action warning is gone and the OpenShift CLI installation still succeeds.

Written by the indexing model from the issue text.