Fix AppIdleHostTest

- Add CtsDeviceAppUsageTestApp to test case list
- Due to complexity of conditions required to actually
  be inactive, test that an app IS active after launching
  it. This is more important anyways, as there would be
  a negative impact if apps were wrongly put into idle

Change-Id: I8cd7fae7da477fe33f96cc75353ca63ad8680488
3 files changed