controller: supervisord: disabled autorestart for policy-loader

The bug #950 (closed) was likely caused by a last improvements to the policy-loader !1742 (merged). The policy-loader is in the "running" state from the start. Any error while loading rules is treated as a failure of an already running process, causing supervisord to attempt to autorestart the policy-loader.

Autorestart was disabled, and a check for the unexpected exit status was added.

Fixes #950 (closed)