mixedreality - remove service due to Azure service retirement (#5035)

Author: sreallymatt

config/resource-manager.hcl

@@ -383,10 +383,6 @@ service "migrate" {
   available = ["2020-01-01", "2020-07-07"]
   ignore    = ["2023-06-06"]
 }
-service "mixedreality" {
-  name      = "MixedReality"
-  available = ["2021-01-01", "2025-01-01"]
-}
 service "mobilenetwork" {
   name      = "MobileNetwork"
   available = ["2022-11-01", "2024-04-01"]