Fixes #4798: Switch to CFEngine 3.6.0rc1 for Rudder

Co-Authored-By: Nicolas PERRON <nicolas.perron@normation.com>
Merge pull request #326 from Kegeruneku/ust_4798/int/4799_upgrade_to_cfengine_3_6

Fixes #4798: Switch to CFEngine 3.6.0rc1 for Rudder
Revert "Fixes #4798: Switch to CFEngine 3.6.0rc1 for Rudder"

This reverts commit a246c553e88ac82146b264e7b14da773c92e9dba.

This commit introduces regressions, reverting !