Remove tmp and public directories as part of "make setup"

What does this MR do and why?

The tmp directory can contain cached Jest test data. If snapshots or tests, or Jest itself, are updated, tests may fail locally due to a mismatch between what's in your Jest cache and what the newly-updated test expects.

We can avoid this weirdness by clearing the tmp directory (make clean) as part of the dependency update process (make setup).

Screenshots, screen recordings, or links to review app

before	after

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Check out this branch.
2. Run make setup; you'll see "INFO: Removing tmp and public directories..." as the first step.
3. Run yarn test
4. Expected result: no failures

Merge request acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this merge request.