Run unit and integration test separately

[bendrucker]

Integration tests depend on Kubernetes (minikube) and are therefore very slow to start. Rather than just allow integration tests to be skipped, we should run unit and integration tests separately, potentially forgoing the inclusion of integration tests in coverage metrics.

This will allow unit tests to run quickly and fail for basic issues, including un-buildable code. Integration tests can either run after or in parallel.

In addition to go test -short, we have the option to use build tags for tests:

https://mickey.dev/posts/go-build-tags-testing/