[WIP] Fixed test for architecture selection

| Q               | A
| --------------- | ---
| Bug fix?        | no
| New feature?    | no
| BC breaks?      | no
| Deprecations?   | no
| Tests pass?     | yes
| Related tickets | 
| License         | GNU GPL v3

Before: the `setup.ini` was saved to `/etc/setup/` and `<mirror_cache>/`.
After: the `setup.ini` will be saved to `/etc/setup/` and `<mirror_cache>/<arch>/`.