create-coco-aks: don't use the default nodepool in dev setup

It's not really needed and we can halve the costs by deleting it right
away. Deploying the emojivoto demodir in a fresh cluster leads to ~80%
utilization of the one node.

packages/create-coco-aks.sh

@@ -50,6 +50,7 @@ az aks nodepool add \
   --resource-group "${name}" \
   --name nodepool2 \
   --cluster-name "${name}" \
+  --mode System \
   --node-count 1 \
   --os-sku AzureLinux \
   --node-vm-size Standard_DC4as_cc_v5 \
@@ -58,3 +59,8 @@ az aks nodepool add \
 az aks get-credentials \
   --resource-group "${name}" \
   --name "${name}"
+
+az aks nodepool delete \
+  --resource-group "${name}" \
+  --cluster-name "${name}" \
+  --name nodepool1