Add false flag in consider_all_requeses_local

Summary: With this change on a failed request, instead of a debug page, we get a simple error page with the message 'The page you were looking for doesn't exist'

Test Plan: Tested on staging and production webdns4 web apps

Reviewers: #servers, alexk

Reviewed By: #servers, alexk

Subscribers: #servers

Differential Revision: https://repo.grnet.gr/D28