✓ Remove Option to "Remove Border" from tabs and dashboards

[sosiology]

When testing on INT the border option to remove the border from an embedded iframe is still available for tabs and dashboards

Steps to Reproduce

1. Go to https://int.visualize.admin.ch/en/v/CjRciHD7YP7S?dataSource=Prod
2. See Tab layout
3. Click the Embedd button
4. See that the option to remove the border is there for a tab layout
5. Go to https://int.visualize.admin.ch/en/v/F6FU0bjgBEg0?dataSource=Prod
6. See Dashboard
7. Click the Embedd button
8. See that the option to remove the border is there for a tab layout

Expected Behaviour
The option to remove the border should only be possible for single charts (or single URLs)

Originally posted by @sosiology in #1794

[sosiology]

Thanks for the refinement @noahonyejese LGTM 👏