OCPBUGS-5234: azurestack: upi: fix compute scale up

Scaling up a compute machineset will fail in AzureStack UPI with:

```
Message:               failed to create vm $clusterID-worker-mtcazs-2gjsl: failure sending request for machine $clusterID-worker-mtcazs-2gjsl: cannot create vm: compute.VirtualMachinesClient#CreateOrUpdate: Failure sending request: StatusCode=404 -- Original Error: Code="NotFound" Message="The Availability Set '/subscriptions/$subID/resourceGroups/$clusterID-rg/providers/Microsoft.Compute/availabilitySets/$clusterID-cluster' cannot be found."
```

because machinesets follow the IPI pattern of using "$clusterID-cluster"
as the availabilitySet's name, whereas UPI uses "$clusterID-avset". So
let's change UPI to be consistent with IPI.

Another inconsistence is the RHCOS image name: UPI appends "-image" to
the name whereas IPI just uses the "$clusterID".

upi/azurestack/02_storage.json

@@ -18,7 +18,7 @@
   },
   "variables" : {
     "location" : "[resourceGroup().location]",
-    "imageName" : "[concat(parameters('baseName'), '-image')]"
+    "imageName" : "[parameters('baseName')]"
   },
   "resources" : [
     {

upi/azurestack/03_infra.json

@@ -20,7 +20,7 @@
     "masterPublicIpAddressID" : "[resourceId('Microsoft.Network/publicIPAddresses', variables('masterPublicIpAddressName'))]",
     "masterLoadBalancerName" : "[concat(parameters('baseName'))]",
     "masterLoadBalancerID" : "[resourceId('Microsoft.Network/loadBalancers', variables('masterLoadBalancerName'))]",
-    "masterAvailabilitySetName" : "[concat(parameters('baseName'), '-avset')]",
+    "masterAvailabilitySetName" : "[concat(parameters('baseName'), '-cluster')]",
     "internalLoadBalancerName" : "[concat(parameters('baseName'), '-internal')]",
     "internalLoadBalancerID" : "[resourceId('Microsoft.Network/loadBalancers', variables('internalLoadBalancerName'))]",
     "skuName": "Basic"

upi/azurestack/04_bootstrap.json

@@ -40,12 +40,12 @@
     "masterSubnetName" : "[concat(parameters('baseName'), '-master-subnet')]",
     "masterSubnetRef" : "[concat(variables('virtualNetworkID'), '/subnets/', variables('masterSubnetName'))]",
     "masterLoadBalancerName" : "[concat(parameters('baseName'))]",
-    "masterAvailabilitySetName" : "[concat(parameters('baseName'), '-avset')]",
+    "masterAvailabilitySetName" : "[concat(parameters('baseName'), '-cluster')]",
     "internalLoadBalancerName" : "[concat(parameters('baseName'), '-internal')]",
     "sshKeyPath" : "/home/core/.ssh/authorized_keys",
     "vmName" : "[concat(parameters('baseName'), '-bootstrap')]",
     "nicName" : "[concat(variables('vmName'), '-nic')]",
-    "imageName" : "[concat(parameters('baseName'), '-image')]",
+    "imageName" : "[parameters('baseName')]",
     "clusterNsgName" : "[concat(parameters('baseName'), '-nsg')]",
     "sshPublicIpAddressName" : "[concat(variables('vmName'), '-ssh-pip')]"
   },

upi/azurestack/05_masters.json

@@ -46,11 +46,11 @@
     "masterSubnetName" : "[concat(parameters('baseName'), '-master-subnet')]",
     "masterSubnetRef" : "[concat(variables('virtualNetworkID'), '/subnets/', variables('masterSubnetName'))]",
     "masterLoadBalancerName" : "[concat(parameters('baseName'))]",
-    "masterAvailabilitySetName" : "[concat(parameters('baseName'), '-avset')]",
+    "masterAvailabilitySetName" : "[concat(parameters('baseName'), '-cluster')]",
     "internalLoadBalancerName" : "[concat(parameters('baseName'), '-internal')]",
     "sshKeyPath" : "/home/core/.ssh/authorized_keys",
     "clusterNsgName" : "[concat(parameters('baseName'), '-nsg')]",
-    "imageName" : "[concat(parameters('baseName'), '-image')]",
+    "imageName" : "[parameters('baseName')]",
     "numberOfMasters" : 3,
     "vms" : {
       "copy" : [

upi/azurestack/06_workers.json

@@ -50,8 +50,8 @@
     "infraLoadBalancerName" : "[parameters('baseName')]",
     "sshKeyPath" : "/home/core/.ssh/authorized_keys",
     "identityName" : "[concat(parameters('baseName'), '-identity')]",
-    "imageName" : "[concat(parameters('baseName'), '-image')]",
-    "masterAvailabilitySetName" : "[concat(parameters('baseName'), '-avset')]",
+    "imageName" : "[parameters('baseName')]",
+    "masterAvailabilitySetName" : "[concat(parameters('baseName'), '-cluster')]",
     "numberOfNodes" : "[parameters('numberOfNodes')]",
     "vms" : {
       "copy" : [