[flexiglass] Enable overview/recents

Fixes issue where the recents gesture was unavailable in Flexiglass
after unlocking the device.

The idea is to hydrate StatusBarService with the correct disable flags
at the right time and do so exclusively from Flexiglass code.

Fix: 343297387
Flag: com.android.systemui.scene_container
Test: manually verified with CLs on the chain
Test: unit tests included
Change-Id: Iee583e1013793a720d1f2a9558ad7f2b2b436c9f