acp_thread: Render execute tool titles as plain text (#55783)

We had a regression where the labels were being rendered as markdown,
which is usually not what you want on a command

Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [ ] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Release Notes:

- N/A

crates/acp_thread/src/acp_thread.rs

@@ -299,10 +299,15 @@ impl ToolCall {
 
         let subagent_session_info = subagent_session_info_from_meta(&tool_call.meta);
 
+        let label = if tool_call.kind == acp::ToolKind::Execute {
+            cx.new(|cx| Markdown::new_text(title.into(), cx))
+        } else {
+            cx.new(|cx| Markdown::new(title.into(), Some(language_registry.clone()), None, cx))
+        };
+
         let result = Self {
             id: tool_call.tool_call_id,
-            label: cx
-                .new(|cx| Markdown::new(title.into(), Some(language_registry.clone()), None, cx)),
+            label,
             kind: tool_call.kind,
             content,
             locations: tool_call.locations,