Clean up camera test in split properly

- From the comments in the original bug for the test failures, it seems like individually running the tests with ag/25880970 passes, but 3 of them fail when running as a suite.
- When I disable the split test in the suite, all the tests pass. This means likely the test didn't clean up split in shell properly.
- ag/25880970 makes sure that the task bar window isn't attached to app during transition.
- Cleaning split test up with calling mTaskOrganizer.unregisterOrganizerIfNeeded(); before a sleep makes sure the next few tests can run as normal.

Forrest test run link: https://android-build.corp.google.com/builds/abtd/run/L37100030001457200

Bug: 314277509
Test: atest CtsCameraTestCases:android.hardware.multiprocess.camera.cts.CameraEvictionTest

Change-Id: I27c6dac305ae8afcbb1d7f1d8c8c1b8fed0ba141