Cancellable: remove UsingToken usages in tests (#18276)

* Remove Cancellable.UsingToken from tests

The token is now always set inside the cancellable computation

* Release notes

---------

Co-authored-by: Kevin Ransom (msft) <codecutter@hotmail.com>

Author: auduchinok

docs/release-notes/.FSharp.Compiler.Service/9.0.300.md

@@ -15,5 +15,6 @@
 
 * FSharpCheckFileResults.ProjectContext.ProjectOptions will not be available when using the experimental Transparent Compiler feature. ([PR #18205](https://github.com/dotnet/fsharp/pull/18205))
 * Update `Obsolete` attribute checking to account for `DiagnosticId` and `UrlFormat` properties. ([PR #18224](https://github.com/dotnet/fsharp/pull/18224))
+* Remove `Cancellable.UsingToken` from tests ([PR #18276](https://github.com/dotnet/fsharp/pull/18276))
 
 ### Breaking Changes

tests/FSharp.Compiler.Service.Tests/ModuleReaderCancellationTests.fs

@@ -22,7 +22,6 @@ let mutable private wasCancelled = false
 let runCancelFirstTime f =
     let mutable requestCount = 0
     fun () ->
-        use _ = Cancellable.UsingToken cts.Token
         if requestCount = 0 then
             cts.Cancel()
 
@@ -150,12 +149,17 @@ let referenceReaderProject getPreTypeDefs (cancelOnModuleAccess: bool) (options:
 let parseAndCheck path source options =
     cts <- new CancellationTokenSource()
     wasCancelled <- false
-    use _ = Cancellable.UsingToken cts.Token
 
     try
-        match Async.RunSynchronously(checker.ParseAndCheckFileInProject(path, 0, SourceText.ofString source, options), cancellationToken = cts.Token) with
-        | fileResults, FSharpCheckFileAnswer.Aborted -> None
-        | fileResults, FSharpCheckFileAnswer.Succeeded results -> Some results
+        let checkFileAsync = checker.ParseAndCheckFileInProject(path, 0, SourceText.ofString source, options)
+        let result =
+            match Async.RunSynchronously(checkFileAsync, cancellationToken = cts.Token) with
+            | _, FSharpCheckFileAnswer.Aborted -> None
+            | _, FSharpCheckFileAnswer.Succeeded results -> Some results
+
+        Cancellable.HasCancellationToken |> shouldEqual false
+        result
+
     with :? OperationCanceledException ->
         wasCancelled <- true
         None