Fix dangling reference to gcloud alpha API for GCI (should be beta)

This reference to the alpha API was missed (fixed in GCE, but not GCI)

cluster/gce/config-default.sh

@@ -212,7 +212,7 @@ ENABLE_RESCHEDULER="${KUBE_ENABLE_RESCHEDULER:-true}"
 #   new subnetwork will be created for the cluster.
 ENABLE_IP_ALIASES=${KUBE_GCE_ENABLE_IP_ALIASES:-false}
 if [ ${ENABLE_IP_ALIASES} = true ]; then
-  # Size of ranges allocated to each node. gcloud alpha supports only /32 and /24.
+  # Size of ranges allocated to each node. Currently supports only /32 and /24.
   IP_ALIAS_SIZE=${KUBE_GCE_IP_ALIAS_SIZE:-/24}
   IP_ALIAS_SUBNETWORK=${KUBE_GCE_IP_ALIAS_SUBNETWORK:-${INSTANCE_PREFIX}-subnet-default}
   # Reserve the services IP space to avoid being allocated for other GCP resources.

cluster/gce/gci/master-helper.sh

@@ -76,7 +76,7 @@ function replicate-master-instance() {
 function create-master-instance-internal() {
   local gcloud="gcloud"
   if [[ "${ENABLE_IP_ALIASES:-}" == 'true' ]]; then
-    gcloud="gcloud alpha"
+    gcloud="gcloud beta"
   fi
 
   local -r master_name="${1}"