Follow-up from "utils/xcbutils: Use window geometry in device pixels"

The following discussion from !5899 (merged) should be addressed:

• @vladz started a discussion: (+2 comments)

  Draft: I don't like how updateServerGeometry() looks and I need to think how to re-arrange the geometry update flow so X11Window can update the device geometry even though the logical geometry stays the same with the new xwayland scale factor.