testing flags leak into k8sm- and km binaries

[jdef]

flags from the testing and stretchr/testify/mock packages are leaking into our non-test binaries.

upstream work:

• Leaking test resources in non-test binaries kubernetes/kubernetes#21114

mesos go:

• relocate mocks mesos/mesos-go#222

... and there's almost certainly lots of mock.Mock leakage in the k8sm unit/integration tests