CancellationTokenSource is not Disposed in cache tag helpers

[Funbit]

Inside https://github.com/aspnet/Mvc/blob/dev/src/Microsoft.AspNetCore.Mvc.TagHelpers/CacheTagHelper.cs#L80 (ProcessAsync method) there is a CancellationTokenSource instantiation without proper Dispose call.

Also, https://github.com/aspnet/Mvc/blob/dev/src/Microsoft.AspNetCore.Mvc.TagHelpers/DistributedCacheTagHelper.cs#L72 creates a new CancellationTokenSource which is not used anywhere.

I believe these places should be fixed.

[Eilon]

For https://github.com/aspnet/Mvc/blob/dev/src/Microsoft.AspNetCore.Mvc.TagHelpers/CacheTagHelper.cs#L80 I'm not sure what the intention is.

https://github.com/aspnet/Mvc/blob/dev/src/Microsoft.AspNetCore.Mvc.TagHelpers/DistributedCacheTagHelper.cs#L72 is definitely wrong - the CTS isn't even used, so we can just delete it.

@sebastienros can you take a look?

[Eilon]

@sebastienros - can you take a look to see if we need to do something here? Looks like there's at least a small change we need to make?