Support GNOME 3.26+ with no system tray

If I start Talk from Launcher it will close after a few seconds.

After removing @@u %U @@ Talk runs normally:

# cat /var/lib/flatpak/exports/share/applications/com.nextcloud.talk.desktop
[Desktop Entry]
Name=Nextcloud Talk
Comment=Official Desktop client for Nextcloud Talk
GenericName=Video and Chat Communication
#Exec=/usr/bin/flatpak run --branch=stable --arch=x86_64 --command=electron-wrapper --file-forwarding com.nextcloud.talk @@u %U @@
Exec=/usr/bin/flatpak run --branch=stable --arch=x86_64 --command=electron-wrapper --file-forwarding com.nextcloud.talk 
Icon=com.nextcloud.talk
Type=Application
StartupNotify=true
Categories=Network;InstantMessaging;Chat;VideoConference;
X-Flatpak=com.nextcloud.talk

I use Gnome3 on Debian Bookworm Back Ports.

# cat /etc/apt/preferences.d/99-backports 
Package: *
Pin: release n=bookworm-backports
Pin-Priority: 500

ii  gnome                                    1:43+1                 amd64        Full GNOME Desktop Environment, with extra components
ii  xserver-xorg                   1:7.7+23                 amd64        X.Org X server
ii  xwayland                        2:22.1.9-1       amd64        X server for running X clients under Wayland

Reproduce the failure by launching Talk from the GNOME application launcher on the reported Debian GNOME setup, then compare it with the modified desktop entry shown in the issue. Trace how the Electron desktop entry handles the file-forwarding arguments; done means the packaged application remains open when launched normally with those arguments present.