Only enable chaiwala-user-session-wayland on target and development images
The chaiwala-user-session-wayland package conflicts with lightdm and cause issues such as the user being unable to mount vbox additions.
This fix updates the image recipe to only enable chaiwala-user-session-wayland on target and development images.
Apertis: https://phabricator.apertis.org/T5017
Signed-off-by: Andre Moreira Magalhaes andre.magalhaes@collabora.co.uk