chore: Update license files with Kubernetes Author copyright

[jonathan-innis]

Fixes #N/A

Description

This PR adds the Kubernetes Author copyright attribution needed after a repo contribution to kubernetes-sigs as called out by: kubernetes/org#4562 (comment). After discussing with @mrbobbytables offline, we came to the conclusion that we should only add the "Kubernetes Authors" attribution here in order to satisfy the copyright constraints that were passed-off from upstream since we didn't find any prior art for adding additional copyright headers to the remainder of the files.

How was this change tested?

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[coveralls]

Pull Request Test Coverage Report for Build 7027733163

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.04%) to 79.529%

---

Totals
Change from base Build 7026638973:	0.04%
Covered Lines:	7972
Relevant Lines:	10024

---

💛 - Coveralls

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jonathan-innis, njtran

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [jonathan-innis,njtran]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[k8s-ci-robot]

@jonathan-innis: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-karpenter-test-1-27	16a0475	link	false	/test pull-karpenter-test-1-27
pull-karpenter-test-1-26	16a0475	link	false	/test pull-karpenter-test-1-26
pull-karpenter-test-1-28	16a0475	link	false	/test pull-karpenter-test-1-28
pull-karpenter-test-1-29	16a0475	link	false	/test pull-karpenter-test-1-29

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.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.

[njtran]

/lgtm