Integration tests imported e2e test code and the dependency made two drawbacks:
- Hard to move test/e2e/framework into staging (#74352)
- Need to run integration tests always even if PRs are just changing e2e test code
This enables import-boss check for blocking such dependency.
This allows us to start building real dependencies into Makefile.
Leave old hack/* scripts in place but advise to use 'make'. There are a few
rules that call things like 'go run' or 'build/*' that I left as-is for now.
