compositor: Don't use cogl_texture_new_with_data in the obvious cases

It's a deprecated API that can surprise us. Namely, when the internal
format passed is COGL_PIXEL_FORMAT_ANY, it will *always* allocate an
RGBA8888 pixel format texture, even if we only passed it a RGB format
or even an A8 format.

cogl_texture_2d_new_with_data is the newer, better API and doesn't have
these warts.