Prevent TaskView's task from getting trimmed by Recents

- When moveTaskToFront() is called with the flag MOVE_TASK_WITH_HOME,
  recents trims the embedded task.
- Send a WindowContainerTransaction to make taskview's task as non-trimmable.
- TaskView's should manage the embedded task.
- Remove setInterceptBackPressedOnTaskRoot() from
  handleAndNotifyTaskRemoval() since it results in a no-op when the task
is being removed. Removed corresponding tests.

Bug: 358682563
Flag: EXEMPT (bug fix)
Test: open app grid, adb shell input keyevent KEYCODE_BACK, verify if embedded task opens
Test: atest CtsWindowManagerDeviceMultiDisplay:android.server.wm.multidisplay.MultiDisplayClientTests TaskViewTest
Change-Id: Ie07eab84293e0694fa6d2c07f056932c08ddff08