reset the csv and yml iterator on file readers

| Q                    | A
| -------------------- | ---
| Bug fix?             | No
| New feature?         | No
| BC breaks?           | No
| CI currently passes? | Yes
| Tests pass?          | Yes
| Scenarios pass?      | Yes (ORM: 1044 - ODM: 76)
| Checkstyle issues?   | No
| Changelog updated?   | Yes
| Fixed tickets        | PIM-2835
| Doc PR               |