The test package imports cmd/kubeadm, which is far from ideal.
There are a couple of reasons for the import:
1) Marshaling of Ingress from api/extensions/v1beta1.

To fix that include a local function in e2e/manifest/manifest.go
that does that same as the kubeadm MarshalToYaml.

2) Using PKI helper function in apimachinery and auth tests.

To fix that include a new file under test/utils/pki_helpers.go
that only contains the required helpers instead of including the whole
kubeadm pkiutil package.

There is another related problem:
e2e_node/e2e_node_suite_test.go includes:
k8s.io/kubernetes/cmd/kubeadm/app/util/system

But this has to be done in a follow up.