Pointwise heuristics incorrect memory access estimation

Hmm... I don't think the original code of this part makes sense. The unit of cur_transfer_size and right_transfer_size were in the unit of byte ^ N, where N is the number of dimensions on the left/right of the break point. My PR will change it to bit ^ N, so in this sense, my PR is NOT a no-op. But I believe we should not block my PR because of this. Instead, we should fix it in a later PR.

Originally posted by @zasdfgbnm in https://github.com/NVIDIA/Fuser/pull/4748#discussion_r2199798284