tests: attach the surface's buffer when moving it
tests: attach the surface's buffer when moving it

move_client() needs to attach the buffer, even if it was attached already,
because since 184df50 configure() will be called only on newly attached
surfaces, but the one that sets the test surface position is the configure
function.

Gnurou/weston,eyolfson/weston,Tarnyko/weston-xdg_surface_present,jonnylamb/weston,Fantu/compositor-spice,krezovic/weston,xorgy/weston,Fantu/compositor-spice,udoprog/weston,sir-murray/weston,krezovic/weston,xorgy/weston,kwm81/weston,kwm81/weston,jonnylamb/weston,Gnurou/weston,eyolfson/weston,giucam/weston,mchalupa/weston,udoprog/weston,giucam/weston,sir-murray/weston,Tarnyko/weston-xdg_surface_present,mchalupa/weston,Fantu/compositor-spice