Shortcut helper should not show up on Locked Screen

We are now only triggering shortcut helper after keyguard has been
dismissed so the user is forced to authenticate(enter
pin/password/biometric) if available, before shortcut helper opens. The
reason for this is that with the shortcut customizer feature, it is now
unsafe for shortcut helper to be accessed from the lock screen as a
random person could  pick up a device, and change shortcuts without the
owner's consent

Test: atest ShortcutHelperCoreStartableTest
Flag: com.android.systemui.keyboard_shortcut_helper_shortcut_customizer
Fix: 381246414
Change-Id: I347e54a7ca81e87cc0b772f99f69df3267ea1f0a