Brake noise when coming to a full stop

I have a 07 prius and for about a year now when I come to a full stop and press the brake completely or apply the parking brake, I get a small squeaky noise (This is separate from the brake pump noise that i have had since new).

The noise is more like when rubbing two pieces of metal together.

I actually was not even bothered by this noise, but during my last service the toyota dealer made a note indicating brake was good, but there is a noise. The service tech then indicated that it "could" be a failing ABS actuator and it would cost 3k to replace it.

I took my car in to brakemasters to see what they tell and they told me everything looks fine with the brakes.. no issues. They recommended a brake fluid flush and changing to ceramic pads because they are less noisy. I did both. The noise still remains only when I come to a complete stop.

Now, I just want to understand if this really can be an ABS issue. If so, would it not trigger some diagnostic light. Also, I want to know if there is even a remote chance of any safety issue here. I drive with my kids in this car and safety is of course most important here.