Cannot empty the packagings

[monsieurtanuki]

What

• We can add or remove packaging components.
• But we cannot empty that list.

Steps to reproduce the behavior

1. Go to a product
2. Go to "edit packaging components"
3. Remove all the components
4. They'll still be there

Expected behavior

We should be able to remove altogether the packaging components.

Additional context

It's probably because in the "save product" process, we consider that "there are no packaging components" means "there are no changes on the packaging components".