Update Phabricator repositories

Summary:
The libphutil repository isn't needed anymore.

The Arcanist repository can be cloned from our version,
so we've directly the patches to fix production, like
phpunit and flake8 fixes.

Test Plan: Deploy on new WindRiver server

Reviewers: aceppaluni

Reviewed By: aceppaluni

Maniphest Tasks: T2017

Differential Revision: https://devcentral.nasqueron.org/D3458