[WIP] [BLOCKER] Fix/cache clearer

| Q                    | A
| -------------------- | ---
| Bug fix?             | Yes
| New feature?         | No
| BC breaks?           | Yes
| CI currently passes? | WIP
| Tests pass?          | Yes
| Scenarios pass?      | Yes
| Checkstyle issues?*  | No
| PMD issues?**        |
| Changelog updated?   | Yes
| Fixed tickets        |
| Doc PR               |

Fixes the cache clearer for non product entities. Also adds a complete flush at the end of each step, to avoid problems between individual steps.
extra lines are removed by php-cs-fixer too