Revert "Revert "Revert "Show "Add users from lock screen" dependent on secure lock screen."""

This reverts commit fa922697.

Reason for revert: b/152587665 - Toggle should always be visible

Bug: 152587665
Test: m RunSettingsRoboTests ROBOTEST_FILTER=AddUserWhenLockedPreferenceControllerTest
Change-Id: I93e58b36965387187b4d1ed03ca2f572728157b9