Camera: DistortionMapper: Move FACE_RECTANGLES to point list

Face rectangles are actually a pair of points, not rects with
(top, left, width, height).

This is very silly but what can you do.

Test: Check metadata output with forced-on distortion correction
Bug: 74434422
Change-Id: I5c0ede9624a198f1dd68328c2dcfa6788ed2d9d9