create contributor-site staging registry

Signed-off-by: Prajyot-Parab <prajyot.parab2@ibm.com>

Author: Prajyot-Parab

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

@@ -21,6 +21,7 @@ locals {
     aws-encryption-provider         = "group:k8s-infra-staging-provider-aws@kubernetes.io"
     charts                          = "group:k8s-infra-release-admins@kubernetes.io"
     cloud-provider-kind             = "group:k8s-infra-staging-kind@kubernetes.io"
+    contributor-site                = "group:k8s-infra-staging-contributor-site@kubernetes.io"
     cluster-capacity                = "group:k8s-infra-staging-cluster-capacity@kubernetes.io"
     dra-driver-cpu                  = "group:k8s-infra-staging-dra-driver-cpu@kubernetes.io"
     dra-example-driver              = "group:k8s-infra-staging-dra-example-driver@kubernetes.io"