Remove BUBBLE_EXPANDED state from ScrimController

I don't think this is needed at all after removing
bubble scrim from ScrimController.

Additionally, this fixes the issue where QS didn't
have a background when pulled down on top of bubbles.

Test: manual - expand a bubble & pull down the shade
             => verify QS look normal
             - expand a bubble, tap the manage button,
               collapse the bubble & pull down the shade
             => verify QS look normal
Test: atest ScrimControllerTest
Bug: 191338071
Bug: 191769064
Change-Id: Ie7aaec551700c823cce5cf6f4ea4f650b640ab63