Remove scrim view alpha when bubble manage menu is shown.

Updated logic for taskbar scrim view alpha calculation, setting it to 0
when bubble manage menu is shown.

Fixes: 337169457
Flag: NONE
Test: Visual.
For gesture navigation:
1) On foldable phone while device is being folded expand any
bubble, click mange button, then unfold. Observe no scrim view is
visible.
2) Enable persistent taskbar, pull down the notification shade then
swipe it back up while bubbles are open.
3) Enable persistent taskbar, pull down the notification shade then
swipe it back up while bubbles and mange menu is open.
4) Enable persistent taskbar. Fold device. Open bubble and click manage
button. Unfold device. Observe no scrim view is visible.

For 3 button navigation
1) Unfold the device, press the home key, pull down the notification
shade then swipe it back up while bubbles are open.
2) Unfold the device, press the home key, pull down the notification
shade then swipe it back up while bubbles and mange menu is open.
3) Fold device, open bubble and click manage button. Unfold device.
Observe no scrim view is visible.

Change-Id: Ic011ae9bd11801a479062cc51c60377823a926fb