In my experience, it's unusual for squeaking to come from the interaction between the pad face and the disc itself, and Bosch is a well respected manufacturer of both discs and pads, so I'd discount that for now.
Personally, I always fit the anti-rattle shims and smear some copper grease on both faces of the shim, to lubricate any high speed movement between the shim and the piston or between the shim and the back of the pad.
Another area to clean up and copper grease are the "ledges" in the caliper that the pads locate on and slide in, the grease tending to slow corrosion in that area and keep the pad movement free.
Just a thought, highly unlikely I know, but the Jazz pads use a small, springy "tang" of metal to rub against the disc and make a horrible squeaking noise when the pad has almost worn down to nothing. It's a very simple, very effective way of letting you know that the pads need changing as the noise will drive you mad. Perhaps just check those on the pads?
