Disable xconsole pipeline in rsyslog

Summary:
On Debian arm, rsyslog offers a default configuration file
defining a xconsole pipeline. But xconsole isn't installed
on some servers. We so disable it.

This suppresses the following log flood:

Sep 11 01:25:01 eglide rsyslogd-2007: action 'action 9' suspended, next retry is Sun Sep 11 01:26:31 2016 [v8.16.0 try http://www.rsyslog.com/e/2007 ]

Reference: http://kb.monitorware.com/kbeventdb-detail-id-6925.html

Fixes T806.

Test Plan: Tested on Eglide, message disappeared from the log.

Reviewers: Sandlayth

Maniphest Tasks: T806

Differential Revision: https://devcentral.nasqueron.org/D673