Fix hovered/pressed states of colorized notification backgrounds

After the notification color scheme updates, colorized notifications
would turn un-colorized when hovered or pressed.

The culprit was a ColorStateList created in NotificationBackgroundView
that didn't actually base the hovered and pressed states on the tint
color.

I'm not sure how this *ever* worked, but this CL bases *all* of the
states on the tint color, and fixes the problem.

Bug: 277285099
Bug: 310318993
Test: manual: find or post a colorized notification and long-press it
Flag: NA
Change-Id: I9a7431c2dadd5703858e84e887979a4c0bd75b30