Revert "On device lockdown, always show the keyguard"

This reverts commit 100ae423.

Reason for revert: b/300463732 regression
Bug: 300463732
Bug: 218495634
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:996896e672f28aa96a3d8158192de3cd4a105bc3)
Merged-In: Ida8f2ab5e4ac79b38c21ba7bacfe9c374c9cc600
Change-Id: Ida8f2ab5e4ac79b38c21ba7bacfe9c374c9cc600