Recent `wrapGAppsHook` change stops `adwaita-icon-theme` from being added to `XDG_DATA_DIRS`:
b1e73fa2e0
Since `display-manager.service` does not have `/run/current-system/sw/share` in `XDG_DATA_DIRS`, it does not pick up the globally installed icon theme either, preventing icons from showing.
Let’s make Adwaita available to fix that for now.
Fixes: https://github.com/NixOS/nixpkgs/issues/171692