Gate adding DeviceLocalAccountPolicies to system logs on device being managed, not user

Before we were checking whether the current user is managed, and if they
are we provide with the public/kiosk user policies in exported JSON file.
Now we check whether the device is managed. This way system logs can
access the public/kiosk policies being in the login screen.

Bug: 875205, 928596
Change-Id: Iccd801f77b8c90aca8980a4d28d01692737ae4f8
Reviewed-on: https://chromium-review.googlesource.com/c/1458177


Commit-Queue: Askar Aitzhan <askaraitzhan@google.com>
Reviewed-by: Matt Menke <mmenke@chromium.org>
Reviewed-by: Sergey Poromov <poromov@chromium.org>
Reviewed-by: Ivan Šandrk <isandrk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#634144}