Remove assistant hints (#21171)

This reverts #20824 and #20899. After adding them last week we came to
the conclusion that the hints are too distracting in everyday use, see
#21128 for more details.

Release Notes:

- N/A

crates/zed/src/main.rs

@@ -61,7 +61,7 @@ use zed::{
     OpenRequest,
 };
 
-use crate::zed::{assistant_hints, inline_completion_registry};
+use crate::zed::inline_completion_registry;
 
 #[cfg(feature = "mimalloc")]
 #[global_allocator]
@@ -407,7 +407,6 @@ fn main() {
             cx,
         );
         assistant2::init(cx);
-        assistant_hints::init(cx);
         repl::init(
             app_state.fs.clone(),
             app_state.client.telemetry().clone(),