policy_readers: Add attestation

Attestationd needs to read device policy to get customerId for VAChallengeRequest flows.

BUG=chromium:1073974
TEST=None

Cq-Depend: chromium:2306261
Change-Id: I2f6857ff79e4695a894a5ddda1b849ba92a98d0e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/eclass-overlay/+/2287474
Tested-by: Igor <igorcov@chromium.org>
Commit-Queue: Igor <igorcov@chromium.org>
Reviewed-by: Leo Lai <cylai@google.com>
Reviewed-by: Igor <igorcov@chromium.org>
Reviewed-by: Mattias Nissler <mnissler@chromium.org>
(cherry picked from commit 8bb568eccec2f8380f6aeb1f2bfd2be90be274c5)
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/eclass-overlay/+/2307374
Auto-Submit: Igor <igorcov@chromium.org>
Commit-Queue: Leo Lai <cylai@google.com>
diff --git a/profiles/base/accounts/group/policy-readers b/profiles/base/accounts/group/policy-readers
index 41f2e86..0e76e2a 100644
--- a/profiles/base/accounts/group/policy-readers
+++ b/profiles/base/accounts/group/policy-readers
@@ -1,4 +1,4 @@
 # Members have read access to the device policy in /var/lib/whitelist.
 group:policy-readers
 gid:303
-users:authpolicyd,chronos,u2f,shill
+users:attestation,authpolicyd,chronos,u2f,shill