data: Disable Xwayland splash screen
We cannot reasonably assume Xwayland to follow the Ubuntu Touch/Lomiri app lifecycle model since it is a proxy for other apps to present window contents to the shell. So do two things:
- Remove X-Ubuntu-Touch to avoid confusion about its lifecycle management
- Hide the splash screen that otherwise gets drawn before first frame presentation
This has the benefit of avoiding Xwayland getting stuck by closing a splash screen before the app has an opportunity to present the first frame to the shell.