Fix not able to start a shortcut into split

Add back flags to allow start background activities since besides
drag-and-drop, start a shortcut into split also need these permission.

Fix: 243101552
Test: atest StageCoordinatorTests
Test: long press on a shortcut to enter split
Change-Id: I9159734836183c811642dffe1a9faebb2ccc23a5
2 files changed