Consolidate the starting window leash relative position.

There would also need to create a animation leash when transfer splash
screen window, consolidate the shift position together so there won't
flickering after reparent.

Bug: 223924102
Test: Launch transfer splash screen app in landscape mode, verify no
flicker.

Change-Id: Iab1cd7d21e87a99d14c46204483d2a1087527125