Show work profile apps only on app list.

For the work profile drilldown, we used to show all apps when the user
drilled down into the categories. This makes it so that the drill down
only shows the work apps when that deep.

Change-Id: I492cd3e9b9b923b87b68645a871dcfb2b91b4f95
Fixes: 62963093
Test: Settings robotest