Trace bitmap dialog: Preview for pixel art tracing only shows blurred grayscale image
#### Summary:
See screenshot:
#### Steps to reproduce:
- open Inkscape
- import small raster image (e.g. 32x32) and keep selected
- open Path > Trace Bitmap > Pixel art
- check preview
#### What happened?
Preview does not have any similarity to the result (grayscale, blurry).
#### What should have happened?
Preview should be similar to the result (color, sharp).
#### Version info
```
Inkscape 1.2-alpha1 (8f0a9a86ab, 2022-03-30)
GLib version: 2.64.6
GTK version: 3.24.20
glibmm version: 2.64.2
gtkmm version: 3.24.2
libxml2 version: 2.9.10
libxslt version: 1.1.34
Cairo version: 1.16.0
Pango version: 1.44.7
HarfBuzz version: 2.6.4
OS version: Linux Mint 20.3
```
issue