PIM-3368: Fix association transformer

| Q                    | A
| -------------------- | ---
| Bug fix?             | Y
| New feature?         | N
| BC breaks?           | N
| CI currently passes? | Y
| Tests pass?          | ?
| Scenarios pass?      | ?
| Checkstyle issues?*  | N
| PMD issues?**        | N
| Changelog updated?   | Y
| Fixed tickets        | PIM-3368
| DB schema updated?   | N
| Migration script?    | N
| Doc PR               |
Yes. Be homogeneous
https://github.com/akeneo/pim-community-dev/pull/1895/files#diff-4abc6f413ed9f653c4ba37168b1bb207L14