Show dots in overflow

BadgedImageView#shouldDrawDot hides the icon if there are any
suppression flags. Remove FLYOUT_VISIBLE flag for overflow icons, since
we don't show flyouts for overflow bubbles.

Fixes: 148878911
Test: manual: unopened bubbles show dots in overflow
Test: manual: opened bubbles do not show dots in overflow
Change-Id: I26147f75b479cb28eedd910135e8e5bc00ecef14