caddy-frontend: Follow up upgrade to ATS 8

Changes:

 * traffic_cop was removed, so use traffic_manager directly
 * logging.config was changed to logging.yaml
 * made records.config and storage.config similar to original files
 * proxy.config.admin.synthetic_port option was removed
 * proxy.config.process_manager.mgmt_port option was removed
 * test: ignore traffic.out in logs
 * test: update ATS version
 * pqsn field was removed and replaced with shn, so follow upstream:
   https://github.com/apache/trafficserver/commit/b0969c91ebc52b37f4c3195ec17d4d0c1c18650c
 * add a test to prove squid.log working, as upgrade resulted with not
   created file