remove variable that v3 doesn't support

Author: lonegunmanb

variables.tf

@@ -1529,18 +1529,6 @@ variable "ultra_ssd_enabled" {
   description = "(Optional) Used to specify whether the UltraSSD is enabled in the Default Node Pool. Defaults to false."
 }
 
-variable "upgrade_override" {
-  type = object({
-    force_upgrade_enabled = bool
-    effective_until       = optional(string)
-  })
-  default     = null
-  description = <<-EOT
-    `force_upgrade_enabled` - (Required) Whether to force upgrade the cluster. Possible values are `true` or `false`.
-    `effective_until` - (Optional) Specifies the duration, in RFC 3339 format (e.g., `2025-10-01T13:00:00Z`), the upgrade_override values are effective. This field must be set for the `upgrade_override` values to take effect. The date-time must be within the next 30 days.
-  EOT
-}
-
 variable "vnet_subnet_id" {
   type        = string
   default     = null