Replace styfle/cancel-workflow-action

[dopplershift]

We should be able to do with with built in concurrency settings in GitHub Actions:

concurrency:
  group: ${{ github.workflow}}-${{ github.head_ref }}
  cancel-in-progress: true

Would eliminate some complexity and an external dependency.

[brian-rose]

I think it would be helpful (from a maintenance perspective) to harmonize the build-and-preview infrastructure for Foundations with what we're doing with Cookbooks.

Once things settle down on the Cookbook front, we should migrate the Cookbook infrastructure to this repo. That would be a good opportunity to eliminate the cancel-workflow-action dependency.

[brian-rose]

Opened #335 to discuss migrating Cookbook infrastructure to this repo. I think we're ready to implement this.

[brian-rose]

Closing since we're using the Cookbook infrastructure now for Foundations.