Ignore sensitive policies on unmanaged Macs

This is approved and can be enabled.

Bug: 1084222
Change-Id: I4bcf0c0347e6eaa9ee7abb12dad54e4addda8aaf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2304773


Reviewed-by: Julian Pastarmov <pastarmovj@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791475}