Snap currently has a bug in which the require cache is not correctly cleared
when running in filter mode (#tests < 2 * #workers).
- We're currently clearing all entries in the require cache of worker threads,
including `jest-worker` and `snap/dist/...` files
- jest-worker seems to `require` these files on every dispatch (i.e.
`worker.compile` seems to call `require(`compiler-worker`).compile`)