ServiceEndPoint not supported in South Africa North.

When trying to deploy ARO cluster in Azure Region South Africa North (southafricanorth).

Not able to deploy because ServiceEndpoints are not supported.

According to #166 South Africa North is supported (GA).

**Command:**
```
az network vnet subnet create \
--resource-group $RESOURCEGROUP \
--vnet-name aro-vnet \
--name master-subnet \
--address-prefixes 10.0.0.0/23 \
--service-endpoints Microsoft.ContainerRegistry
```

**Output:**

> Virtual networks in southafricanorth location do not support ServiceEndpoints for Microsoft.ContainerRegistry service and subscription 'ID Number'.