chore: fix license header references #622

Job	Run time
Test Core on EKS (upstream) / test-eks-install	1h 11m 38s
Test Core on EKS (unicorn) / test-eks-install	1h 13m 37s
Test Core on EKS (registry1) / test-eks-install	1h 8m 24s
Test Core on RKE2 (registry1) / test-rke2-install	42m 21s
Test Core on RKE2 (upstream) / test-rke2-install	41m 45s
Test Core on RKE2 (unicorn) / test-rke2-install	40m 46s
	5h 38m 31s

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