[dashboard_copy] Some card metadata (e.g. alternate column titles) is not copied

[hellpe]

Steps to reproduce:

1. Create a card (e.g. Table) and add it to a dashboard
2. Edit the card vizualisation settings and modify the title of a column (then save the changes)
3. Use dashboard_copy to copy the dashboard containing the card
4. Check the copied card

Expected result:
The column has reverted to its original name

[hellpe]

Tested with https://metabase.osp.cat/question/6034-propositions-triees-par-commentaires-soutiens copied to https://metabase.osp.cat/question/6584-propositions-triees-par-commentaires-soutiens:

• some column names are correctly copied ("Nombre de commentaires", "Nombre de soutiens") but not others ("Titre" is reverted to "Title")
• the "URL" setting is not carried upon: