Disable user switching when the device is factory resetting.

On automotive, a factory reset request from the device admin can be
delayed as it would be a driving hazard, but the user should not be
switchable during this state.

Test: atest FrameworksMockingServicesTests:FactoryResetterTest
Test: manual verification using TestDpc

Fixes: 205874492
Bug: 225012970

Change-Id: I2b6cd7c56bf3714ccf79b9b092c8b67dd5817f0c