[upv5]

Wheel bearings normally rumble rather than squeak and on the front the noise increases or decreases as you corner as the load increases or decreases. Squeaking is often a stone or other foreign object getting stuck between disc and dust shield which is why your mechanic pushed the dust shield away from the disc.
However the ABS is triggered by magnets built into the bearing and metallic particles can be attracted to the magnets and upset the ABS which triggers the "Anti skid warning". First step is to clean the magnets and Volvo recommend pushing an air line into the small gaps and giving the area a good blow out ideally as the wheel is turned.
The best thing about this is it's free if you have access to an air line.

John