use NSM_KUBERNETES_VERSION variable to specify k8s version for clusters #724

Job	Run time
interdomain	10m 53s
checkgomod / checkgomod	11s
shellcheck / shellcheck	12s
golangci-lint / golangci-lint	21s
exclude-fmt-errorf / exclude-fmt-errorf	3s
yamllint / yamllint	24s
	12m 4s

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