Always initialize FLAG_ALWAYS_UNLOCKED DCs unlocked

When adding a new display to a locked device, any keyguard state should
normally be copied. However there is an exception if the new display
does not support locking at all.

Flag: com.android.window.flags.ensure_keyguard_does_transition_starting_bug_fix
Test: atest 'ActivityTaskManagerServiceTests#testSetLockScreenShownWithAlwaysUnlockedVirtualDisplay'
Fix: 446174085
Bug: 436770343
Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:4ff0b946ac8c2cb141d5d305d05c4ced5b167387
Merged-In: I8540ffb35fa8cb27fa7159f64f3daf7d7658adbe
Change-Id: I8540ffb35fa8cb27fa7159f64f3daf7d7658adbe