Use faster build for the default minikube target
Use faster build for the default minikube target

When we are doing the "cross" compile targets, we
force rebuilding all packages (up-to-date or not).

For the default native target "out/minikube", we
can do a much faster build (10x!), for development.

Leaving all the cross target to rebuild, as before.

Also the _test.go files are only used for unit tests.

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