m3: Refine AlertDialog style

Aligns AlertDialog to match material spec
Notable display size previews:
- w192dp HSV before: https://hsv.googleplex.com/6471489439137792
- w192dp HSV after: https://hsv.googleplex.com/4766563348512768

- w216dp HSV before: https://hsv.googleplex.com/6596150697132032
- w216dp HSV after: https://hsv.googleplex.com/5441350492225536

More HSV links in issue tracker

Flag: android.widget.flags.use_wear_material3_ui
Bug: 372623420
Test: manual
Change-Id: Ia03614adffdd1b31b1f3f7d5243794d686e4479d