Optimize string building for NamespacedName

[markusthoemmes]

What type of PR is this?

What this PR does / why we need it:

This applies a microoptimization to the String() function of types.NamespacedName. It's something we carry around downstream and I don't quite see a reason not to upstream it.

Based on this benchmark

func BenchmarkNamespacedName(b *testing.B) {
	name := types.NamespacedName{
		Namespace: "test-namespace",
		Name:      "test-name",
	}

	for i := 0; i < b.N; i++ {
		_ = name.String()
	}
}

The results are

benchmark                      old ns/op     new ns/op     delta
BenchmarkNamespacedName-16     187           18.9          -89.89%

benchmark                      old allocs     new allocs     delta
BenchmarkNamespacedName-16     3              0              -100.00%

benchmark                      old bytes     new bytes     delta
BenchmarkNamespacedName-16     64            0             -100.00%

Which is almost too good to be true 😂. Maybe I'm missing something obvious here.

Does this PR introduce a user-facing change?:

NONE

[k8s-ci-robot]

Hi @markusthoemmes. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[markusthoemmes]

/assign @liggitt

[liggitt]

/lgtm
/approve
/ok-to-test

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: liggitt, markusthoemmes

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[liggitt]

/priority backlog
/kind cleanup

[markusthoemmes]

/test pull-kubernetes-bazel-test

[fedebongio]

/triage accepted