fix clippy errors

net/gce.sh

@@ -481,7 +481,7 @@ EOF
   num_zones=${#zones[@]}
   numNodesPerZone=$((additionalFullNodeCount / num_zones))
   numLeftOverNodes=$((additionalFullNodeCount % num_zones))
-  for ((i=0; i < $num_zones; i++)); do
+  for ((i=0; i < "$num_zones"; i++)); do
     zone=${zones[i]}
     if [[ $i -eq $((num_zones - 1)) ]]; then
       numNodesPerZone=$((numNodesPerZone + numLeftOverNodes))