Remove Onionoo's lock file
Onionoo still creates a lock file and fails to start if such a file is present. But the main reason for that file was to avoid concurrent runs triggered by hourly cronjobs. This wouldn't happen anymore, because Onionoo uses its own scheduler to start runs. The only possible issue we're preventing is that the operator runs another Onionoo process in parallel. But CollecTor doesn't use a lock file, either. Is it time to remove Onionoo's lock file? Removing the lock file would make the start script somewhat simpler.