ensure that network policy can be GC'd

[deads2k]

fixes https://bugzilla.redhat.com/show_bug.cgi?id=1516228

This updates GC to give us error messages and updates the network policy validation to allow GC-ing

@jwforres fyi

[deads2k]

/retest

[mfojtik]

/lgtm

[openshift-merge-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: deads2k, mfojtik

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Needs approval from an approver in each of these OWNERS Files:

• vendor/k8s.io/kubernetes/pkg/apis/OWNERS [deads2k,mfojtik]
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[openshift-bot]

/retest

Please review the full test history for this PR and help us cut down flakes.

[openshift-ci-robot]

@deads2k: The following test failed, say /retest to rerun them all:

Test name	Commit	Details	Rerun command
ci/openshift-jenkins/extended_conformance_install_update	8a1912a	link	/test extended_conformance_install_update

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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[openshift-merge-robot]

Automatic merge from submit-queue.