Rewrite e2e tests in Go

[norbjd]

For now, e2e tests are written in bash: https://github.com/norbjd/k8s-pod-cpu-booster/blob/main/test/e2e-kind.sh.

This was convenient to bootstrap the project, but when we need to add new tests (e.g. #16), this becomes a nightmare. And now it's difficult to maintain.

I'd like to rewrite tests in Go.