Account for the bouncer's scrim in LightBarController

1) The ScrimController's alpha is irrelevant when the bouncer is showing, because the bouncer's scrim is baked into that view, so we always want `forceForScrim` to be true when the bouncer is showing.
2) Moreover, the bouncer covers expanded QS, so tweak the later logic to ignore the QS override when the bouncer is visible.

Fixes: 280434803
Test: atest LightBarControllerTest
Change-Id: Id4236235ce11b473d64d36431c9a4e5f70caf2c9