Revert "On device lockdown, always show the keyguard"

This reverts commit b23c2d5f.

Reason for revert: b/300463732 regression
Bug: 300463732
Bug: 218495634
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:f57217125f2b124c16c463ef4507fb054cc1ba4f)
Merged-In: I31485d0d8caa3060e998636b071dbe03f6b4fc82
Change-Id: I31485d0d8caa3060e998636b071dbe03f6b4fc82