[Bugfix] Fix the issue of transition animation splash screen in split screen mode.

When an app enters split-screen mode, the mAnimatingActivityRegistry of the current Activity still comes from the app's Task, but the mAnimatingActivityRegistry of the newly opened Activity comes from the split-screen Task, so there is no guarantee that the animation-leash of the transition animation will be destroyed at the same time.
So we ensure that the mAnimatingActivityRegistry of ActivityRecord under the same Task is the same after entering split screen mode, so as to ensure that the transition animation of activity opening and closing ends at the same time, thereby avoiding splash screen.

Bug: 204024254
Test: Above scenario
Change-Id: Ibf0fccecefaa8768b4e10f69a064a4b7452dcaa9
Signed-off-by: shicheng <shicheng@xiaomi.com>