FIX: Sort plugin list by name properly (#24839)

Some plugins have discourse- prefixed on their name
and some don't, so sorting in the list was inconsistent.

---------

Co-authored-by: Ted Johansson <ted@discourse.org>

app/controllers/admin/plugins_controller.rb

@@ -2,6 +2,10 @@
 
 class Admin::PluginsController < Admin::StaffController
   def index
-    render_serialized(Discourse.visible_plugins, AdminPluginSerializer, root: "plugins")
+    render_serialized(
+      Discourse.visible_plugins.sort_by { |p| p.name.downcase.delete_prefix("discourse-") },
+      AdminPluginSerializer,
+      root: "plugins",
+    )
   end
 end