Create tests for workflows that we ship from the creators package

Create tests for workflows that we ship from the creators package, like the build-extension-chart, which triggers the reusable workflow. This covers problems with the shipped workflow, which we found recently as per:

https://github.com/rancher/dashboard/pull/12636 https://github.com/rancher/dashboard/pull/12637 https://github.com/rancher/dashboard/pull/12638

We are already covering the actual reusable workflow with https://github.com/rancher/dashboard/issues/12032 (dependent on that work)

rancher / dashboard

Create tests for workflows that we ship from the creators package #12657