My brakes are making a kind of groaning/ creaking noise when the car is not being driven and the sound goes away when i press the brakes or put the hand brake on, it happens when the car is on mostly flat ground with very slight slopes facing forward or back, usually if in nuetral the car would move slightly but the car won’t move in neutral and thats when the groaning/ creaking noise would start but if the slope is steep enough the car would roll forward or back when left in neutral with no brakes applied, could this be a sticking calliper or the brake pads just sticking to the rotor ? I will show photo of my front brakes as the back brakes look fine