Have workflow engine test suites run all flows

[Andrew-S-Rosen]

What new feature would you like to see?

We should figure out some way to refactor the workflow engine test suites so they run every flow. This will help catch bugs earlier, like #1742. The challenge is we want to avoid copy/paste, but they all are called in different ways, e.g. Client() for Dask, .result() calls for some and not others. Still, I'd rather do copy/paste than have untested code altogether.