Remove COMPOSE_BOUNCER_ENABLED enabled static flag

with the removal of SCENE_CONTAINER_ENABELD, most of the compose and
flexiglass dependencies are already part of the main sysui APK.

This flag is not needed anymore and isn't making a big difference to
odex file size

Flag: ACONFIG com.android.systemui.compose_bouncer DEVELOPMENT
Test: everything builds, no bloatbuster warning
Bug: 280877228
Bug: 310005730
Change-Id: I08a52ebe5cfe7c2bdfd327b219d7f26d91c81d35