Delete knative webhooks during KF uninstalling

[akrava]

Fixes #435.

I propose to delete knative webhooks, which causes an error after reinstall, during Kubeflow deletion process.

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Hi @akrava. Thanks for your PR.

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[akrava]

@googlebot I signed it!

[Jeffwan]

/cc @Tomcli @adrian555 @shawnzhu

[Jeffwan]

I tried to optimize deletion order and components in this PR. #386

Can you check is there's something you can reuse?

[akrava]

Hi @Jeffwan! Thanks for asking. Unfortunately I cannot reuse anything from your PR due situation described in issue #435, which I'm trying to solve in my PR, is a little bit different. If I understand correctly, PR #386 optimize deletion in case if user deletes KF using client tool kfctl, due to your code is using in Delete method, which is called from 'kfctl delete ...':

kfctl/pkg/kfapp/kustomize/kustomize.go

Lines 366 to 367 in 23ae5c1

	// Delete is called from 'kfctl delete ...'. Will delete all resources deployed from the Apply method
	func (kustomize *kustomize) Delete(resources kftypesv3.ResourceEnum) error {

But my situation differ: I'm using operator and I delete KF resources by kubectl delete -f kfdef/kfctl_k8s_istio.v1.1.0.yaml and then delete operator itself. Generally all KF resources have got ownerReferences definition in metadata so it is deleting simultaneously with KF, but unfortunately knative remove ownerReferences from some webhooks after startup. This why I proposed such workaround.

[Jeffwan]

@akrava sounds good. Let's wait for folks who working on operator from @kubeflow/wg-deployment-leads to review your change. I am not familiar with controller logic

[Jeffwan]

/assign @kubeflow/wg-deployment-leads
/cc @Tomcli @shawnzhu