Revert "Replace SUBNET_ID source. (#530)" (#539)

This reverts commit f9ed254.

hack/deploy/configure-values.sh

@@ -31,11 +31,12 @@ BOOTSTRAP_TOKEN=$TOKEN_ID.$TOKEN_SECRET
 SSH_PUBLIC_KEY="$(cat ~/.ssh/id_rsa.pub) azureuser"
 
 if [[ ! -v VNET_SUBNET_ID ]]; then
-    # Getting the subnet id from the first AgentPoolProfile in the cluster
-    VNET_SUBNET_ID=$(jq -r ".agentPoolProfiles[0].vnetSubnetId" <<< "$AKS_JSON")
+    # first subnet of first VNet found
+    VNET_JSON=$(az network vnet list --resource-group "$AZURE_RESOURCE_GROUP_MC" | jq -r ".[0]")
+    VNET_SUBNET_ID=$(jq -r ".subnets[0].id" <<< "$VNET_JSON")
 fi
 
-# The // empty ensures that if the files is 'null' or not present jq will output nothing
+# The // empty ensures that if the files is 'null' or not prsent jq will output nothing
 # If the value returned is none, its from jq and not the aks api in this case we return ""
 NETWORK_PLUGIN=$(jq -r ".networkProfile.networkPlugin // empty | if . == \"none\" then \"\" else . end" <<< "$AKS_JSON")
 NETWORK_PLUGIN_MODE=$(jq -r ".networkProfile.networkPluginMode // empty | if . == \"none\" then \"\" else . end" <<< "$AKS_JSON")