Enable Channels for everyone (#4058)

[[PR Description]]

Release Notes:

- Adds Channels, a new mechanism for collaboration. [Read
More...](https://zed.dev/blog/channels)

crates/collab_ui/src/collab_ui.rs

@@ -12,7 +12,6 @@ use std::{rc::Rc, sync::Arc};
 use call::{report_call_event_for_room, ActiveCall};
 pub use collab_panel::CollabPanel;
 pub use collab_titlebar_item::CollabTitlebarItem;
-use feature_flags::{ChannelsAlpha, FeatureFlagAppExt};
 use gpui::{
     actions, point, AppContext, GlobalPixels, Pixels, PlatformDisplay, Size, Task, WindowBounds,
     WindowKind, WindowOptions,
@@ -121,7 +120,3 @@ fn notification_window_options(
         display_id: Some(screen.id()),
     }
 }
-
-fn is_channels_feature_enabled(cx: &gpui::WindowContext<'_>) -> bool {
-    cx.is_staff() || cx.has_flag::<ChannelsAlpha>()
-}