[virtualbox] The GUI shows the first public IP shows as a private IP

**Describe the bug**
VirtualBox instances have no private IP outside of VirtualBox. Multipass usually displays N/A in the CLI, as well as in the GUI, under the "Private IP". However, in instances that have other interfaces, the first extra IP is shown as the private IP.

**To Reproduce**
1. `multipass launch --network `
1. Navigate to the "All instance page in the GUI" and look at the "Private IP" column.

**Expected behavior**
I would expect the public IP to be listed in the "Public IP" column, with N/A being kept for "Private IP"

**Additional info**
- `multipass get local.driver`: `virtualbox`

Reproduce with `multipass launch --network ` using the VirtualBox driver, then open the GUI's All instance page and inspect how the Private IP and Public IP columns are populated. Done means the extra public interface address appears under Public IP while Private IP remains N/A when the instance has no private IP.

Written by the indexing model from the issue text.