Cleanup History file

[dmanners]

Preconditions (*)

1. 2.3-develop
2. phpstan installed composer require --dev phpstan/phpstan

Steps to reproduce (*)

1. run ./vendor/bin/phpstan analyse -l 0 app/code/Magento/ImportExport/Model/History.php

Expected result (*)

1. No errors

Actual result (*)

 1/1 [▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓] 100%

 ------ -------------------------------------------------------------------------------
  Line   History.php
 ------ -------------------------------------------------------------------------------
  66     Access to an undefined property Magento\ImportExport\Model\History::$session.
  313    Access to an undefined property Magento\ImportExport\Model\History::$session.
  314    Access to an undefined property Magento\ImportExport\Model\History::$session.
 ------ -------------------------------------------------------------------------------


 [ERROR] Found 3 errors

[dmanners]

Covered by PR #150