Remove the ability to book onboarding (#31404)

Closes: https://github.com/zed-industries/zed/issues/31394

Onboarding has been valuable, but we're moving into a new phase as our
user base grows, and our ability to chat with everyone who books a call
will not scale linearly. For now, we are removing the option to book a
call from the application.

Release Notes:

- N/A

crates/title_bar/src/title_bar.rs

@@ -38,7 +38,7 @@ use ui::{
 };
 use util::ResultExt;
 use workspace::{Workspace, notifications::NotifyResultExt};
-use zed_actions::{OpenBrowser, OpenRecent, OpenRemote};
+use zed_actions::{OpenRecent, OpenRemote};
 
 pub use onboarding_banner::restore_banner;
 
@@ -49,8 +49,6 @@ const MAX_PROJECT_NAME_LENGTH: usize = 40;
 const MAX_BRANCH_NAME_LENGTH: usize = 40;
 const MAX_SHORT_SHA_LENGTH: usize = 8;
 
-const BOOK_ONBOARDING: &str = "https://dub.sh/zed-c-onboarding";
-
 actions!(collab, [ToggleUserMenu, ToggleProjectMenu, SwitchBranch]);
 
 pub fn init(cx: &mut App) {
@@ -734,13 +732,6 @@ impl TitleBar {
                             zed_actions::Extensions::default().boxed_clone(),
                         )
                         .separator()
-                        .link(
-                            "Book Onboarding",
-                            OpenBrowser {
-                                url: BOOK_ONBOARDING.to_string(),
-                            }
-                            .boxed_clone(),
-                        )
                         .action("Sign Out", client::SignOut.boxed_clone())
                     })
                     .into()
@@ -784,14 +775,6 @@ impl TitleBar {
                                 "Extensions",
                                 zed_actions::Extensions::default().boxed_clone(),
                             )
-                            .separator()
-                            .link(
-                                "Book Onboarding",
-                                OpenBrowser {
-                                    url: BOOK_ONBOARDING.to_string(),
-                                }
-                                .boxed_clone(),
-                            )
                     })
                     .into()
                 })

crates/welcome/src/welcome.rs

@@ -29,7 +29,6 @@ actions!(welcome, [ResetHints]);
 
 pub const FIRST_OPEN: &str = "first_open";
 pub const DOCS_URL: &str = "https://zed.dev/docs/";
-const BOOK_ONBOARDING: &str = "https://dub.sh/zed-c-onboarding";
 
 pub fn init(cx: &mut App) {
     BaseKeymap::register(cx);
@@ -254,16 +253,6 @@ impl Render for WelcomePage {
                                                 ), cx);
                                             })),
                                     )
-                                    .child(
-                                        Button::new("book-onboarding", "Book Onboarding")
-                                            .icon(IconName::PhoneIncoming)
-                                            .icon_size(IconSize::XSmall)
-                                            .icon_color(Color::Muted)
-                                            .icon_position(IconPosition::Start)
-                                            .on_click(cx.listener(|_, _, _, cx| {
-                                                cx.open_url(BOOK_ONBOARDING);
-                                            })),
-                                    ),
                             ),
                     )
                     .child(