Make our test suite compatible with a Wayland Tails

• Our test suite uses xdotool, that only partly works on Wayland:
  • xdotool set_desktop N still works
  • xdotool key Super doesn’t
    • The super ("windows") key is KEY_LEFTMETA (0x7d)
  • xdotool search --name only works for apps that are not Wayland native
    • We don't need this if we can drop usage of windowactivate and windowmove
  • xdotool ... windowactivate ?
    • Pidgin: it's going away (#8573) hopefully before we switch to Wayland
    • Installer: waiting with OpenCV for the Installer to appear should be good enough
  • xdotool ... windowmove ?
    • If we fix the underlying bug this workarounds, we're good.
    • Note: I cannot reproduce with Tails running Wayland! So we're probably good!
    • And actually there is an alternative workaround that I have verified works: @screen.press('super', 'up'). So we're definitely good here!