Drop unnecessary json.Marshal

[soltysh]

What type of PR is this?

/kind cleanup
/sig cli

What this PR does / why we need it:

I've spotted that while looking through @brianpursley 's #109085

yaml.Marshal under the covers invokes json.Marshal and then JSONToYAML conversion which was done here manually.
See here:

kubernetes/vendor/sigs.k8s.io/yaml/yaml.go

Lines 16 to 28 in 03d0e2c

	func Marshal(o interface{}) ([]byte, error) {
	j, err := json.Marshal(o)
	if err != nil {
	return nil, fmt.Errorf("error marshaling into JSON: %v", err)
	}
	y, err := JSONToYAML(j)
	if err != nil {
	return nil, fmt.Errorf("error converting JSON to YAML: %v", err)
	}
	return y, nil
	}

Which issue(s) this PR fixes:

None

Special notes for your reviewer:

/assign @ardaguclu

Does this PR introduce a user-facing change?

NONE

[soltysh]

/triage accepted
/priority backlog

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: soltysh

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[ardaguclu]

/lgtm

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