fix care_of when editing prepared shipments

[andrecedik]

The parameter care_of wasn't shown when editing a prepared shipment, although it was provided in the first place. This led to problems when creating shipping labels, because the value now was missing.

Since sender addresses do not have a care_of, I've also removed the input and replaced it with a spacer, so the forms still look identical

What has changed?

• The input for recipients care_of will now be populated when it was filled previously.

Please read the commit messages for details.

Things to review

Common things:

• [x] Works fine.
• [x] Changelog written or not needed.
• [x] No conflict with current branch.