Fixes to remove controls for tablet

These fixes are needed in order for the following:
* No part of the controls tree is accessible when the flag is off
* The tile comes back once the flag is on

Test: manually flash changing handheld_core_hardware.xml
Test: atest AutoTileManagerTest DeviceControlsControllerImplTest
Bug: 268204890
Change-Id: I030ecbbf77feef0f342826d568210ac24bd2c141