assistant_context_editor: Remove suggest edits (#30286)

This PR removes the code for the "Suggest Edits" functionality from
Assistant1.

This feature was already disabled entirely with the launch of the Agent,
we're just cleaning up the unused code.

Release Notes:

- N/A

crates/prompt_store/src/prompts.rs

@@ -443,10 +443,6 @@ impl PromptBuilder {
             .lock()
             .render("terminal_assistant_prompt", &context)
     }
-
-    pub fn generate_suggest_edits_prompt(&self) -> Result<String, RenderError> {
-        self.handlebars.lock().render("suggest_edits", &())
-    }
 }
 
 #[cfg(test)]