buffet: Removed "owner" from localAnonymousAccessMaxRole

Final set of roles does not include owner here.

BUG=brillo:947
TEST=FEATURE=test emerge-gizmo privetd

Change-Id: I5ff11cdc7a48f99c480bb5ab357f32ce82b80003
Reviewed-on: https://chromium-review.googlesource.com/270677
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Vitaly Buka <vitalybuka@chromium.org>
Tested-by: Vitaly Buka <vitalybuka@chromium.org>