Handle updates removing remaining finalizers on deleted objects

[liggitt]

What type of PR is this?
/kind bug

What this PR does / why we need it:
Avoids making all finalizer implementers do a separate delete after removing their finalizer

Which issue(s) this PR fixes:
Fixes #77944

Does this PR introduce a user-facing change?:

Updates that remove remaining `metadata.finalizers` from  an object that is pending deletion (non-nil metadata.deletionTimestamp) and has no graceful deletion pending (nil or 0 metadata.deletionGracePeriodSeconds) now results in immediate deletion of the object.

/sig api-machinery
/cc @caesarxuchao

[caesarxuchao]

The approach lgtm.

Please add a unit test to ensure the namespace delete behavior is correct.

We need to update namespace controller and crd finalizer logic, these lines should be redundant now:

kubernetes/pkg/controller/namespace/deletion/namespaced_resources_deleter.go

Lines 157 to 159 in aaec77a

	if d.deleteNamespaceWhenDone && finalized(namespace) {
	return d.deleteNamespace(namespace)
	}

kubernetes/staging/src/k8s.io/apiextensions-apiserver/pkg/controller/finalizer/crd_finalizer.go

Lines 158 to 159 in aaec77a

	// and now issue another delete, which should clean it all up if no finalizers remain or no-op if they do
	return c.crdClient.CustomResourceDefinitions().Delete(crd.Name, nil)

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: liggitt

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• pkg/controller/OWNERS [liggitt]
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• staging/src/k8s.io/apiextensions-apiserver/OWNERS [liggitt]
• staging/src/k8s.io/apiserver/OWNERS [liggitt]
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[liggitt]

Please add a unit test to ensure the namespace delete behavior is correct.

done, added positive and negative unit tests for spec and metadata finalizers on namespace update and finalize storage

We need to update namespace controller and crd finalizer logic, these lines should be redundant now

added TODOs to remove redundant deletes in the next release (I'd rather be extra sure we don't block namespace or CRD cleanup in a controller/apiserver skew scenario)

[liggitt]

/retest

[caesarxuchao]

/lgtm

[liggitt]

/priority important-soon