PIM 2916  - MongoDB Completeness in the grid is lost after saving the product

| Q                    | A
| -------------------- | ---
| Bug fix?             | Yes
| New feature?         | No
| BC breaks?           | Yes
| CI currently passes? | No
| Tests pass?          | Yes
| Scenarios pass?      | In progress
| Checkstyle issues?   | No
| Changelog updated?   | Yes
| Fixed tickets        | PIM-2916
| Doc PR               | N.A.