nixos/gnome: Do not force Qt apps to Adwaita

adwaita-qt tries valiantly to ensure a visual consistency
but unfortunately, it often falls into an uncanny valley instead.
Let’s make it opt-in again for more vanilla default experience.

Related: https://pagure.io/fedora-workstation/issue/351

nixos/doc/manual/release-notes/rl-2311.section.md

···
 
 - The Cinnamon module now enables XDG desktop integration by default. If you are experiencing collisions related to xdg-desktop-portal-gtk you can safely remove `xdg.portal.extraPortals = [ pkgs.xdg-desktop-portal-gtk ];` from your NixOS configuration.
 
+- GNOME module no longer forces Qt applications to use Adwaita style since it was buggy and is no longer maintained upstream. If you still want it, you can add the following options to your configuration but it will probably be eventually removed:
+
+  ```nix
+  qt = {
+    enable = true;
+    platformTheme = "gnome";
+    style = "adwaita";
+  };
+  ```
+
 - `fontconfig` now defaults to using greyscale antialiasing instead of subpixel antialiasing because of a [recommendation from one of the downstreams](https://gitlab.freedesktop.org/fontconfig/fontconfig/-/issues/337). You can change this value by configuring [](#opt-fonts.fontconfig.subpixel.rgba) accordingly.
 
 - The latest available version of Nextcloud is v27 (available as `pkgs.nextcloud27`). The installation logic is as follows:

nixos/modules/services/x11/desktop-managers/gnome.nix

···
         })
       ];
 
-      # Harmonize Qt application style and also make them use the portal for file chooser dialog.
-      qt = {
-        enable = mkDefault true;
-        platformTheme = mkDefault "gnome";
-        style = mkDefault "adwaita";
-      };
-
       networking.networkmanager.enable = mkDefault true;
 
       services.xserver.updateDbusEnvironment = true;