Run setCurrentPage in applyLoadPlan after scroll initialized

- Also combined the 2 setCurrentPage call in applyLoadPlan into 1
- Otherwise setCurrentTask may set to page 1 unexpectedly due to page 0's scroll being invalid and out of range

Bug: 246283207
Bug: 238461210
Test: Split screen with 2 apps, click back, go to overview again, should snap to focsued task
Change-Id: I3b57655c810668fe244659437fbd4a745ca02d21