message: style(common): remove `FutureExt::boxed` to unify project style
diff: use std::mem;
  +use futures_util::FutureExt as _;
  use tokio_sync::{mpsc, watch};
  use super::{Future, Never, Poll, Pin, task};
  -use futures_util::FutureExt as _;
  // Sentinel value signaling that the watch is still open
  enum Action {
  @@ -100,9 +100,10 @@ where
  loop {
  match mem::replace(&mut me.state, State::Draining) {
  State::Watch(on_drain) => {
  - let mut recv_fut = me.watch.rx.recv_ref().boxed();
  + let recv = me.watch.rx.recv_ref();
  + futures_util::pin_mut!(recv);
  - match recv_fut.poll_unpin(cx) {
  + match recv.poll_unpin(cx) {
  Poll::Ready(None) => {
  // Drain has been triggered!
  on_drain(unsafe { Pin::new_unchecked(&mut me.future) });
  