NE-1324: Make caller-reference unique for AWS PHZ creation

The caller-reference when creating a private hosted zone needs to be
unique. In some pre-submit job run situations, it reuses the cluster
name, causing caller-reference to reused. This solution simply adds a
timestamp to caller reference to always ensure it's unique.

ci-operator/step-registry/aws/provision/route53/private-hosted-zone/aws-provision-route53-private-hosted-zone-commands.sh

@@ -18,7 +18,10 @@ CLUSTER_NAME="${NAMESPACE}-${UNIQUE_HASH}"
 
 ROUTE53_HOSTED_ZONE_NAME="${CLUSTER_NAME}.${BASE_DOMAIN}"
 VPC_ID=$(cat "${SHARED_DIR}/vpc_id")
-CALLER_REFERENCE_STR=$ROUTE53_HOSTED_ZONE_NAME
+# Use a timestamp to ensure the caller reference is unique, as we've found
+# cluster name can get reused in specific situations.
+TIMESTAMP=$(date +%s)
+CALLER_REFERENCE_STR="${ROUTE53_HOSTED_ZONE_NAME}-${TIMESTAMP}"
 
 echo -e "creating route53 hosted zone: ${ROUTE53_HOSTED_ZONE_NAME}"
 HOSTED_ZONE_CREATION=$(aws --region "$REGION" route53 create-hosted-zone --name "${ROUTE53_HOSTED_ZONE_NAME}" --vpc VPCRegion="${REGION}",VPCId="${VPC_ID}" --caller-reference "${CALLER_REFERENCE_STR}")