Changed deprecated TF resource (azurerm_virtual_machine)

quickstart/101-vm-cluster-linux/variables.tf

@@ -0,0 +1,11 @@
+variable "resource_group_location" {
+  type        = string
+  description = "Location for all resources."
+  default     = "eastus"
+}
+
+variable "resource_group_name_prefix" {
+  type        = string
+  description = "Prefix of the resource group name that's combined with a random ID so name is unique in your Azure subscription."
+  default     = "rg"
+}