fix: Add a 'use' around linked cancellation tokens

[nordfjord]

I noticed that a lot of the objects that were surviving in my memory leak repro were CancellationTokenSources

Adding a use seems to solve for our memory leak

Before

After

See this related stack overflow https://stackoverflow.com/questions/6960520/when-to-dispose-cancellationtokensource

[CLAassistant]

All committers have signed the CLA.

[bartelink]

Thanks! And great to have the details and charts to accompany it