Moves the embedded task to back when it become invisible

UIAutomator can't find UIObject under invisible embedded task.
This wont affect the devices with Shell Transition enabled like phone and TV because they take the different code path.

Bug: 295906315
Test: atest com.android.car.pm.CarPackageManagerServiceTest#testBlockingActivity_DoLaunchesNonDoOnCreate_isBlocked --iterations 50
Change-Id: I7e55a06bab9daf85622e3149f82485bc0afddf05