Disable Lock Task Mode before enabling it

In certain circumstances, if another app initiates Lock Task Mode before the DLC does, it can subsequently break the DLC's lock. This fixes that vulnerability by ending any pre-existing Lock Task Mode before DLC starts its own.

Bug: 288396685
Test: Manual with test app defined in ag/24426052
Test: atest DeviceLockControllerRoboTests
Change-Id: I87ef568b683155bdf8fd3612ca07d56ad958cf38
1 file changed