Limit blocked test to logged in users.

The value is currently set in HTML so will be cached for anonymous
users where IP is blocked and thus cannot be relied on unless we know
we have busted the cache. As a result only set this config variable
for logged in users.

Bug: 60993
Change-Id: I94e2e51626998c97aa89d0bee4e99f3d0c2aef4c
Merge "Limit blocked test to logged in users."