The Manticore service starts on boot, and may be started before a MongoDB database server is available.
Currently, the startup for Manticore requires MongoDB to be available and ready, but really the only thing the service starting can depend on is network.
If we were to make the Manticore service to depend on mongod.service, then this locks in a single-host deployment, and does not allow for an external MongoDB service to be used.
We would rather not have Manticore not error out fatally, but instead retry (with an interval to prevent endlessly looping tirelessly).