Trims Recent Task when Task windowing mode changed after dismiss split-screen

While starting an activity in split-screen, a Task was created in
multi-window mode and added to the RecentTasks. Once the activity is
finished, the same Task was reparented to TDA and became fullscreen
windowing mode before the activity is removed.

The next time starting the same activity in split-screen, a multi-window
mode Task was added to the RecentTasks again without trimming the legacy
recent Task because the windowing modes are incompatible (multi-window
vs. fullscreen). Repeating the steps could resulted in redundant tasks
in Recents.

Bug: 289317239
Test: atest RecentTasksTest
Change-Id: I7af0acaa6d528d7a45018b1b7f57dbe6d57f1585