samsung-a3ulte, samsung-serranovelte: fix Phosh scaling, make ui elements bigger

Scaling fix

The scaling for Phosh on samsung-a3ulte was wrong.
See this example picture: Despite the small 4" screen, the main menu has 5 columns of icons (the PinePhone has 4)

I found out that scaling can be changed my modifying the scale factor inside /etc/phosh/rootston.ini
In my opinion changing from scale=1 to scale=1.5 results in the best UI scaling factor. \

This is Phosh with scale=1.5, with PinePhone for comparison

Note

I set the scaling to 1.5 also for samsung-serranovelte, which has the same screen resolution, as suggested by @Minecrell.

Wallpaper issue

The only drawback is that setting scale=1.5 makes the wallpaper cover only part of the screen,
Anyone knows how to solve this?

Update

I've changed the background picture options with gsettings set org.gnome.desktop.background picture-options scaled and I've also tried other values listed here https://help.gnome.org/admin/system-admin-guide/stable/backgrounds-extra.html.en But the background seems to cover only part of the screen.

I think this may be a phosh bug.