Fix tasks not being stopped on reruns (#29786)

Follow-up of https://github.com/zed-industries/zed/pull/28993

* Tone down tasks' cancellation logging
* Fix task terminals' leak, disallowing to fully cancel the task by
dropping the terminal off the pane:

f619d5f02a/crates/terminal_view/src/terminal_panel.rs (L1464-L1471)

Release Notes:

- Fixed tasks not being stopped on reruns

crates/terminal/src/terminal.rs

@@ -46,7 +46,7 @@ use smol::channel::{Receiver, Sender};
 use task::{HideStrategy, Shell, TaskId};
 use terminal_settings::{AlternateScroll, CursorShape, TerminalSettings};
 use theme::{ActiveTheme, Theme};
-use util::{ResultExt, paths::home_dir, truncate_and_trailoff};
+use util::{paths::home_dir, truncate_and_trailoff};
 
 use std::{
     cmp::{self, min},
@@ -1851,8 +1851,7 @@ impl Terminal {
         if let Some(task) = self.task() {
             if task.status == TaskStatus::Running {
                 let completion_receiver = task.completion_rx.clone();
-                return cx
-                    .spawn(async move |_| completion_receiver.recv().await.log_err().flatten());
+                return cx.spawn(async move |_| completion_receiver.recv().await.ok().flatten());
             } else if let Ok(status) = task.completion_rx.try_recv() {
                 return Task::ready(status);
             }