Add staging registry for kubemark

Signed-off-by: Davanum Srinivas <davanum@gmail.com>

Author: dims

infra/gcp/terraform/k8s-staging-images/registries.tf

@@ -27,6 +27,7 @@ locals {
     ingate                          = "group:k8s-infra-staging-ingate@kubernetes.io"
     jobset                          = "group:k8s-infra-staging-jobset@kubernetes.io"
     kind                            = "group:k8s-infra-staging-kind@kubernetes.io"
+    kubemark                        = "group:sig-scalability-leads@kubernetes.io"
     kubernetes                      = "group:k8s-infra-staging-kubernetes@kubernetes.io"
     kueue                           = "group:k8s-infra-staging-kueue@kubernetes.io"
     lws                             = "group:k8s-infra-staging-lws@kubernetes.io"