Ensure no management api for v12 (#14197)

* Remove management api

* Remove actual files

tests/Umbraco.Tests.UnitTests/Umbraco.Core/Telemetry/SiteIdentifierServiceTests.cs

@@ -1,4 +1,3 @@
-using System;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Moq;

tests/Umbraco.Tests.UnitTests/Umbraco.Core/Telemetry/TelemetryServiceTests.cs

@@ -1,4 +1,3 @@
-using System;
 using System.Collections.Generic;
 using System.Linq;
 using Moq;