cli: Remove service management functionality

The Tracker 3 CLI contains some flags to manage the Tracker services, e.g. tracker daemon --kill|--terminate|--start, tracker reset --hard.

This functionality was implemented before Upstart and systemd introduced more standard vocabulary for managing system services. These days, we can expect that users have systemctl --user stop tracker-miner-fs-3.service or an equivalent command available, and Tracker doesn't need to reimplement service management itself.