Replace tasks in the same split with the dropping app

When launching a new app into a specific split, evicts all child tasks
that were originally in the same split.

Fix: 202739668
Test: atest WMShellUnitTests
Test: manual check dropping an app to a specific split evicts other
      tasks in the same split.
Change-Id: I3f52a3675d6ead742f0b75c83393462e5778a524