TryGetSuggestedActionSets does not handle cancellation correctly

[tmat]

Version Used:
Version 16.5.0 Preview 3.0 [29804.240.master]

The following exception is reported in activity log (info bar is displayed).

System.OperationCanceledException: The operation was canceled.
   at System.Threading.CancellationToken.ThrowOperationCanceledException()
   at System.Threading.ManualResetEventSlim.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.Threading.Tasks.Task.SpinThenBlockingWait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.Threading.Tasks.Task.InternalWait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at Roslyn.Utilities.TaskExtensions.WaitAndGetResult_CanCallOnBackground[T](Task`1 task, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Editor.Implementation.Suggestions.SuggestedActionsSourceProvider.SuggestedActionsSource.GetCodeFixes(ITextBufferSupportsFeatureService supportsFeatureService, ISuggestedActionCategorySet requestedActionCategories, Workspace workspace, Document document, SnapshotSpan range, Func`2 addOperationScope, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Editor.Implementation.Suggestions.SuggestedActionsSourceProvider.SuggestedActionsSource.GetSuggestedActions(ISuggestedActionCategorySet requestedActionCategories, SnapshotSpan range, IUIThreadOperationContext operationContext, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Editor.Implementation.Suggestions.SuggestedActionsSourceProvider.SuggestedActionsSource.GetSuggestedActions(ISuggestedActionCategorySet requestedActionCategories, SnapshotSpan range, IUIThreadOperationContext operationContext)
   at Microsoft.VisualStudio.Language.Intellisense.Implementation.LightBulbSession.<>c__DisplayClass40_4.<TryGetSuggestedActionSets>b__1()
   at Microsoft.VisualStudio.Text.Utilities.GuardedOperations.CallExtensionPoint[T](Object errorSource, Func`1 call, T valueOnThrow)
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.VisualStudio.Telemetry.WindowsErrorReporting.WatsonReport.GetClrWatsonExceptionInfo(Exception exceptionObject)

[mavasani]

This is a duplicate of #41218, both of them have an unhandled cancellation from Microsoft.VisualStudio.Language.Intellisense.Implementation.LightBulbSession