What is the ruling on men trimming their hair at the nape of the neck, the forehead, and behind the ears with scissors? Does this fall under Qaza’ (shaving part of the head and leaving other parts)?

It appears that this does not fall under the forbidden qaza' (shaved patches), because qaza' is the shaving of a child's head while leaving scattered, unshaven areas. Scholars have unanimously agreed on the disliking of qaza' if it is in scattered areas, except for medical treatment or similar reasons, and this disliking is one of tanzih (disapproval but not outright prohibition).