title: akeneo pim - Move attributes from model to variant not updating raw_values
body: <p>we are using akeneo v4 now and still stumbling over the following issue.
  Our customer is moving an attribute from the common model to the variant. All works fine, but when opening a product model which and saving it an error occures which says that</p>
  <pre><code>Cannot set the property &quot;attribute_name&quot; to this entity as it is not in the attribute set
  </code></pre>
  <p>as this is right because the attribute should not appear in the product-model anymore. Instead it should be in the variant.</p>
  <p>Anyone has a clue why the raw values of the product model is not updated?</p>
  <p>Regards
  Peter</p>