Automatic merge from submit-queue (batch tested with PRs 63969, 63902, 63689, 63973, 63978). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
kubeadm: Remove dependency on pkg/client/clientset_generated/internalclientset
**What this PR does / why we need it**:
This PR removes dependency in kubeadm on `pkg/client/clientset_generated/internalclientset` and blacklists it in `.import-restrictions`.
The above package is pulled in transitively by the usage of the following:
- [GetFlagString](a481f4bbe8/cmd/kubeadm/app/cmd/version.go (L63)) from `k8s.io/kubernetes/pkg/kubectl/cmd/util`
- [LeaseEndpointReconcilerType](a481f4bbe8/cmd/kubeadm/app/phases/controlplane/manifests.go (L205)) from `k8s.io/kubernetes/pkg/master/reconcilers`
Dropping the unneeded dependencies from the build shaves off 4-5MB from the amd64 executable and reduces the dependency hell in kubeadm.
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixeskubernetes/kubeadm#806
**Special notes for your reviewer**:
/cc @kubernetes/sig-cluster-lifecycle-pr-reviews
/area kubeadm
/assign @luxas
/assign @timothysc
**Release note**:
```release-note
NONE
```
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