Fix bug of unit test in printers

[lichuqiang]

What this PR does / why we need it:
Test case TestPrintHumanReadableWithNamespace of printers meant to test the rejection of nonnamespacesd resources from printer with param WithNamespace, i.e logic as below:

func printNamespace(obj *api.Namespace, options printers.PrintOptions) ([]metav1alpha1.TableRow, error) {
	if options.WithNamespace {
		return nil, fmt.Errorf("namespace is not namespaced")
	}
	row := metav1alpha1.TableRow{
		Object: runtime.RawExtension{Object: obj},
	}
	row.Cells = append(row.Cells, obj.Name, obj.Status.Phase, translateTimestamp(obj.CreationTimestamp))
	return []metav1alpha1.TableRow{row}, nil

but due to a lack of statement AddHandlers(printer) in test case, it would always succeed, even though corresponding logic has been removed

Besides, as the rejection logic no longer exists, the test case should be changed to test the relationship between param WithNamespace in printers and output format

Special notes for your reviewer:
/cc @zjj2wry

Release note:

NONE

[k8s-ci-robot]

Hi @lichuqiang. Thanks for your PR.

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[zjj2wry]

/ok-to-test

[derekwaynecarr]

/approve no-issue
/lgtm

[k8s-github-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: derekwaynecarr, lichuqiang
We suggest the following additional approver: pwittrock

Assign the PR to them by writing /assign @pwittrock in a comment when ready.

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• pkg/printers/OWNERS

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[zjj2wry]

/retest

[lichuqiang]

/assign @pwittrock

[lichuqiang]

/retest

[k8s-github-robot]

/test all

Tests are more than 96 hours old. Re-running tests.

[k8s-ci-robot]

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

Test name	Commit	Details	Rerun command
pull-kubernetes-unit	576c636	link	/test pull-kubernetes-unit

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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[fejta-bot]

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/lifecycle stale

[lichuqiang]

Closing the PR since the code has been out of date