UPSTREAM: 41864: Allow 'kubectl drain --force' to remove orphaned pods

[marun]

If the managing resource of a given pod (e.g. DaemonSet/ReplicaSet/etc) is deleted (effectively orphaning the pod), and kubectl drain --force is invoked on the node hosting the pod, the command would fail with an error indicating that the managing resource was not found. This PR reduces the error to a warning if --force is specified, allowing nodes with orphaned pods to be drained.

Reference: https://bugzilla.redhat.com/show_bug.cgi?id=1424678

[derekwaynecarr]

lgtm [merge]

[eparis]

[WARNING] While the jUnit report found no failed tests, the `go test` process failed.
18:07:27 [WARNING] This usually means that the unit test suite failed to compile.
18:07:27 [WARNING] `go test` had the following output to stderr:
18:07:27 vendor/k8s.io/kubernetes/pkg/kubectl/cmd/drain_test.go:281: undefined: metav1 in metav1.ObjectMeta
18:07:27 vendor/k8s.io/kubernetes/pkg/kubectl/cmd/drain_test.go:288: undefined: metav1 in metav1.LabelSelector
18:07:27 vendor/k8s.io/kubernetes/pkg/kubectl/cmd/drain_test.go:296: undefined: metav1 in metav1.ObjectMeta

[marun]

Fixed.

[openshift-bot]

[Test]ing while waiting on the merge queue

[openshift-bot]

Evaluated for origin test up to af13e07

[openshift-bot]

continuous-integration/openshift-jenkins/test FAILURE (https://ci.openshift.redhat.com/jenkins/job/test_pull_requests_origin_future/629/) (Base Commit: f82baba)

[eparis]

[merge] because device mapper is the worst

[openshift-bot]

Evaluated for origin merge up to af13e07

[openshift-bot]

continuous-integration/openshift-jenkins/merge SUCCESS (https://ci.openshift.redhat.com/jenkins/job/test_pull_requests_origin_future/690/) (Base Commit: ceb2cf3) (Image: devenv-rhel7_6008)