Remove webservd user from privetd user group

Callbacks from webservd daemon to privetd's request handler is now
specifically allowed to webservd user and not just privetd user
group.

BUG=brillo:171
TEST=build image, deploy on device and test privetd's http handlers
CQ-DEPEND=CL:247302,CL:247303

Change-Id: Ie291360228faa8adb7a4fb5f693b6f24b481d4c6
Reviewed-on: https://chromium-review.googlesource.com/247270
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
diff --git a/profiles/base/accounts/group/privetd b/profiles/base/accounts/group/privetd
index 2fc356c..8e0af54 100644
--- a/profiles/base/accounts/group/privetd
+++ b/profiles/base/accounts/group/privetd
@@ -1,3 +1,3 @@
 group:privetd
 gid:262
-users:chronos,leaderd,privetd,webservd
+users:chronos,leaderd,privetd