Remove Deferred cancellation on client reset

[KentShikama]

See https://github.com/twisted/klein/issues/546.

We have been running a similar patch on our enterprise production systems for about 6 months with no issues, and critically we have stopped getting issues on client resets.

[adiroiban]

without automated tests is hard to know if this works or not. It might work for your case, but might introduce error to others...

I am not using klein, so I don't know.

It was just a general comment

Also, I am not sure why the CI was not triggered for this PR.

[glyph]

I'm also not sure what's going on with CI; sorry that it's broken. Can you reword / force-push or push another commit to see if it's just a flake on github's side?

[KentShikama]

I'm going to close until discussion at https://github.com/twisted/klein/issues/546 is resolved.