DEV: Remove site_setting_saved event (#15164)

We said we would drop it from 2.4, so this is long overdue

Co-authored-by: Jarek Radosz <jradosz@gmail.com>

lib/site_settings/local_process_provider.rb

@@ -45,7 +45,6 @@ class SiteSettings::LocalProcessProvider
       settings[name] = setting
     end
     setting.value = value.to_s
-    DiscourseEvent.trigger(:site_setting_saved, setting)
     setting
   end