TEP-0142: Use StepAction from Catalog in example

https://github.com/tektoncd/pipeline/pull/7321 introduces remote resolution for StepActions, but the example is not using the ones in [Catalog](https://github.com/tektoncd/catalog) since Catalog hasn't added StepActions. When they are added we should update examples to use StepActions from Catalog.