Settings: Black background option displayed when automatic theme is selected

The black background option is displayed when the theme of the application follows the one of the device and the bright color palette is used.

This option should only be displayed when the dark color palettes are used.

changed milestone to %3.5.0

added Bug Minor labels

assigned to @diogo.simao-marques

mentioned in merge request !1126 (merged)

closed with commit 7aef253d

closed with merge request !1126 (merged)