Remove unneeded 'static lifetimes on &strs in constants (#8698)

This PR removes unneeded `'static` lifetimes on `&str`s stored in
`const` declarations.

This addresses some Clippy lints about
[`redundant_static_lifetimes`](https://rust-lang.github.io/rust-clippy/master/index.html#/redundant_static_lifetimes).

In item-level `const` declarations we can rely on lifetime elision and
use the default `'static` lifetime.

Note that associated constants still require an explicit `'static`
lifetime, as explained in
https://github.com/rust-lang/rust/issues/115010.

Release Notes:

- N/A

crates/collab_ui/src/chat_panel.rs

@@ -34,7 +34,7 @@ use workspace::{
 mod message_editor;
 
 const MESSAGE_LOADING_THRESHOLD: usize = 50;
-const CHAT_PANEL_KEY: &'static str = "ChatPanel";
+const CHAT_PANEL_KEY: &str = "ChatPanel";
 
 pub fn init(cx: &mut AppContext) {
     cx.observe_new_views(|workspace: &mut Workspace, _| {

crates/collab_ui/src/collab_panel.rs

@@ -62,7 +62,7 @@ struct ChannelMoveClipboard {
     channel_id: ChannelId,
 }
 
-const COLLABORATION_PANEL_KEY: &'static str = "CollaborationPanel";
+const COLLABORATION_PANEL_KEY: &str = "CollaborationPanel";
 
 pub fn init(cx: &mut AppContext) {
     cx.observe_new_views(|workspace: &mut Workspace, _| {

crates/collab_ui/src/notification_panel.rs

@@ -29,7 +29,7 @@ use workspace::{
 const LOADING_THRESHOLD: usize = 30;
 const MARK_AS_READ_DELAY: Duration = Duration::from_secs(1);
 const TOAST_DURATION: Duration = Duration::from_secs(5);
-const NOTIFICATION_PANEL_KEY: &'static str = "NotificationPanel";
+const NOTIFICATION_PANEL_KEY: &str = "NotificationPanel";
 
 pub struct NotificationPanel {
     client: Arc<Client>,