transparency.wikimedia.org: 404 until 21pm UTC

The Transparency Report site should not be accessible until 9:00 AM GMT.
This patch adds a rewrite that makes all requests 404 until 21:00 PM UTC
tonight. 404s are good because they aren't cached by Varnish.

If this looks good, I'll follow-up with another patch to set the correct time
for tomorrow.

Change-Id: Idc152d6850315db7ca6ae468c4b7c9385d15c8ff