DEV: Revert 3 commits for plugin API to add directory columns (#13423)

app/models/directory_column.rb

@@ -1,37 +1,5 @@
 # frozen_string_literal: true
 
 class DirectoryColumn < ActiveRecord::Base
-  self.inheritance_column = nil
-
-  def self.automatic_column_names
-    @automatic_column_names ||= [:likes_received,
-                   :likes_given,
-                   :topics_entered,
-                   :topic_count,
-                   :post_count,
-                   :posts_read,
-                   :days_visited]
-  end
-
-  def self.active_column_names
-    DirectoryColumn.where(type: [:automatic, :plugin]).where(enabled: true).pluck(:name).map(&:to_sym)
-  end
-
-  @@plugin_directory_columns = []
-
-  enum type: { automatic: 0, user_field: 1, plugin: 2 }
-
   belongs_to :user_field
-
-  def self.add_plugin_directory_column(name)
-    @@plugin_directory_columns << name
-  end
-
-  def self.plugin_directory_columns
-    @@plugin_directory_columns
-  end
-
-  def self.clear_plugin_directory_columns
-    @@plugin_directory_columns = []
-  end
 end