CancellationToken is not a property on TestContext

### Type of issue

Code doesn't work

### Description

`CancellationToken` is not a property on `TestContext`.
It instead is `CancellationTokenSource`.

### Page URL

https://learn.microsoft.com/en-us/dotnet/core/testing/mstest-analyzers/mstest0049

### Content source URL

https://github.com/dotnet/docs/blob/main/docs/core/testing/mstest-analyzers/mstest0049.md

### Document Version Independent Id

11c7ec45-be3b-5457-c153-7a6e18432673

### Platform Id

a38be9f6-7220-b23e-82fc-69b19cc33c6a

### Article author

@Evangelink

### Metadata

* ID: dcd4363a-81ca-4b25-6147-d0ed5a5f28c0
* PlatformId: a38be9f6-7220-b23e-82fc-69b19cc33c6a
* Service: **dotnet-fundamentals**

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