Fix switching "Swipe down from Show notification" to "Pull screen

into reach" will not able to trigger it at first time

Update notifyShortcutStateChanged() when swipe down from Show
notification settings changed.

Bug: 198395550

Test: manual switch shortcut FAB to test
Test: Test: atest WMShellUnitTests
Change-Id: Ic550586c651a0a6c61f7f672afffbcb83ccf25ff