what:
- runs module and api integration tests in matrix strategy
- v28 of jest comes with sharding support, which we can utilize when we upgrade
- splits the tests by number of matrix jobs and run them in parallel
- This introduced some flakiness in some specs, but couldn't reproduce locally. Those have been skipped for now.
- uses swc/jest for added performance
- Locally, a chunk took 90 seconds with babel and 30 seconds with swc.
- This translated to 2 mins saved per shard in CI, but haven't tested this enough.
