Migrate from futures::task::noop_waker to Waker::noop

Now that our MSRV is >=1.85, we should replace our existing uses of futures::task::noop_waker() and futures::task::noop_waker_ref() with std::task::Waker::noop().

(Bonus points if anyone also wants to replace our uses of self.waker = cx.waker().clone() with self.waker.clone_from(cx.waker()).)