Remove dead Maniphest field config from default.conf.php

Summary: Some day we'll just delete this entirely.

Test Plan: loaded Phabricator

Reviewers: zeeg, btrahan

Reviewed By: zeeg

CC: aran, mbishopim3

Differential Revision: https://secure.phabricator.com/D7044

Author: epriestley

conf/default.conf.php

@@ -929,10 +929,6 @@
 
 // -- Maniphest ------------------------------------------------------------- //
 
-  // Array of custom fields for Maniphest tasks. For details on adding custom
-  // fields to Maniphest, see "Maniphest User Guide: Adding Custom Fields".
-  'maniphest.custom-fields' => array(),
-
   // What should the default task priority be in create flows?
   // See the constants in @{class:ManiphestTaskPriority} for valid values.
   // Defaults to "needs triage".