Revert "Qt: set breeze as the default theme"

This reverts commit 4a6d8f422e.

Adding a dependency to `kde-style-breeze` pulls in around 35 new packages,
for an additional size of 40 MB (unpacked). It's basically a part of the
KDE stack that is installed. Not nice for users who don't run KDE.

etc/xdg/qt5ct/qt5ct.conf

@@ -3,7 +3,7 @@ custom_palette=true
 icon_theme=Flat-Remix-Blue-Dark
 color_scheme_path=/usr/share/qt5ct/colors/Kali-Dark.conf
 standard_dialogs=default
-style=Breeze
+style=Fusion
 
 [Interface]
 stylesheets=/usr/share/qt5ct/qss/fusion-simple-scrollbar.qss