Revert "DEV: add a plugin modifier to change hidden site settings (#24104)" (#24117)

This reverts commit ddcee84e45.

lib/site_setting_extension.rb

@@ -91,12 +91,8 @@ module SiteSettingExtension
     @shadowed_settings ||= []
   end
 
-  def hidden_settings_provider
-    @hidden_settings_provider ||= SiteSettings::HiddenProvider.new
-  end
-
   def hidden_settings
-    hidden_settings_provider.all
+    @hidden_settings ||= []
   end
 
   def refresh_settings
@@ -588,14 +584,14 @@ module SiteSettingExtension
 
       categories[name] = opts[:category] || :uncategorized
 
-      hidden_settings_provider.add_hidden(name) if opts[:hidden]
+      hidden_settings << name if opts[:hidden]
 
       if GlobalSetting.respond_to?(name)
         val = GlobalSetting.public_send(name)
 
         unless val.nil? || (val == "")
           shadowed_val = val
-          hidden_settings_provider.add_hidden(name)
+          hidden_settings << name
           shadowed_settings << name
         end
       end

lib/site_settings/hidden_provider.rb

@@ -1,19 +0,0 @@
-# frozen_string_literal: true
-
-module SiteSettings
-end
-
-# A class to store and modify hidden site settings
-class SiteSettings::HiddenProvider
-  def initialize
-    @hidden_settings = Set.new
-  end
-
-  def add_hidden(site_setting_name)
-    @hidden_settings << site_setting_name
-  end
-
-  def all
-    DiscoursePluginRegistry.apply_modifier(:hidden_site_settings, @hidden_settings)
-  end
-end