Undisposed Cancellation Tokens Sources

There are multiple places with undisposed CancellationTokenSource, potentially leading to leaks due to unreleased memory.

For instance,

Line 286 in 92e0bf3

    
           var cancellation = new CancellationTokenSource(collectionOptions.Value.ActivationTimeout);

Line 367 in 92e0bf3

    
           var timeoutTokenSource = new CancellationTokenSource(this.collectionOptions.Value.DeactivationTimeout);

The issue is opened by comment:
Originally posted by @ReubenBond in #9080 (comment)