Maybe I'm speaking too soon. Darn. Watch. I'll drive it tomorrow and it'll start making noises. But anyway.
I think NickD has finally solved the mystery of my brake noises. He mentioned something about parking brake and rear brakes and eureka. I never used my parking brake. Then I looked it up. Several sources say the same thing:
Troubleshooting
Adjust Caliper Parking Brakes
The GM rear caliper with integral parking brake is self-adjusting when you use the parking brake. As the pads wear it will click to the next stop, but they do not always work and they will not work if you do not use your parking brake.
well. I'll be damned. After a month and a half of multiple visits to my dealer and being told everything was fine, I came back home from my vacation. Got inside my Cruze. Pumped that E Brake stick like 40+ times. Have been using the E Brake every time I park the car religiously, and guess what?
day after. 1 click. Not loud. Some humming noise but muffled. Rear discs started getting a nice pad coating. Turning darker gray.
Couple of days after that. 0 clicks. Maybe 1 humming. Very brief instead of a long dragging sound.
Now, the count 5 days later, 0 clicks. 0 humming noises.
Ill report back next week. I start working. If this works, ill be writing someone to put this information in the Cruze manual. I know it is partly my fault (if that was the issue), but they put warnings and labels for every stupid thing nowadays. Using the parking brake to adjust the rear calipers is something that should be in the manual.
The dealer mechanics should've asked me. Maybe they themselves don't know this.