Merge branch 'ignore-experimental-indexer-column' into 'master'

Ignore elasticsearch_experimental_indexer column [step 1]

See merge request gitlab-org/gitlab!30760

app/models/application_setting.rb

@@ -5,10 +5,13 @@ class ApplicationSetting < ApplicationRecord
   include CacheMarkdownField
   include TokenAuthenticatable
   include ChronicDurationAttribute
+  include IgnorableColumns
 
   GRAFANA_URL_ERROR_MESSAGE = 'Please check your Grafana URL setting in ' \
     'Admin Area > Settings > Metrics and profiling > Metrics - Grafana'
 
+  ignore_column :elasticsearch_experimental_indexer, remove_with: '13.1', remove_after: '2020-05-22'
+
   add_authentication_token_field :runners_registration_token, encrypted: -> { Feature.enabled?(:application_settings_tokens_optional_encryption, default_enabled: true) ? :optional : :required }
   add_authentication_token_field :health_check_access_token
   add_authentication_token_field :static_objects_external_storage_auth_token