Change domain block CSV parsing to be more robust and handle more lists (#21470)

* Change domain block CSV parsing to be more robust and handle more lists

* Add some tests

* Improve domain block import validation and reporting

app/controllers/concerns/admin_export_controller_concern.rb

@@ -26,14 +26,4 @@ module AdminExportControllerConcern
   def import_params
     params.require(:admin_import).permit(:data)
   end
-
-  def import_data_path
-    params[:admin_import][:data].path
-  end
-
-  def parse_import_data!(default_headers)
-    data = CSV.read(import_data_path, headers: true, encoding: 'UTF-8')
-    data = CSV.read(import_data_path, headers: default_headers, encoding: 'UTF-8') unless data.headers&.first&.strip&.include?(default_headers[0])
-    @data = data.reject(&:blank?)
-  end
 end