refactor(native_select): drop hardcoded chevron from NativeSelectIcon

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: pierry01

gem/lib/ruby_ui/native_select/native_select_icon.rb

@@ -25,9 +25,7 @@ def icon
         stroke_linejoin: "round",
         class: "size-4",
         aria_hidden: "true"
-      ) do |s|
-        s.path(d: "m6 9 6 6 6-6")
-      end
+      )
     end
 
     def default_attrs