Fix Rails/BulkChangeTable cop (#26890)

db/migrate/20170624134742_add_description_to_session_activations.rb

@@ -2,8 +2,10 @@
 
 class AddDescriptionToSessionActivations < ActiveRecord::Migration[5.1]
   def change
-    add_column :session_activations, :user_agent, :string, null: false, default: ''
-    add_column :session_activations, :ip, :inet
+    change_table(:session_activations, bulk: true) do |t|
+      t.column :user_agent, :string, null: false, default: ''
+      t.column :ip, :inet
+    end
     add_foreign_key :session_activations, :users, on_delete: :cascade
   end
 end