Ignore unused columns at elastic_reindexing_tasks

ee/app/models/elastic/reindexing_task.rb

 # frozen_string_literal: true
 
 class Elastic::ReindexingTask < ApplicationRecord
+  include IgnorableColumns
+
   self.table_name = 'elastic_reindexing_tasks'
 
+  ignore_columns %i[documents_count index_name_from index_name_to elastic_task documents_count_target], remove_with: '14.0', remove_after: '2021-04-22'
+
   has_many :subtasks, class_name: 'Elastic::ReindexingSubtask', foreign_key: :elastic_reindexing_task_id
 
   enum state: {

ee/spec/factories/elastic/reindexing_tasks.rb

@@ -4,8 +4,6 @@ FactoryBot.define do
   factory :elastic_reindexing_task, class: 'Elastic::ReindexingTask' do
     state { :initial }
     in_progress { true }
-    index_name_from { 'old_index_name' }
-    index_name_to { 'new_index_name' }
 
     trait :with_subtask do
       after(:create) do |task|