Automatically restart mongo components after restore from physical backup

After restoring from a physical backup, mongod instances and pbm-agents will be shutdown. At the moment, users are required to manuall restart these components, but it will be a better experience if we can automatically  restart them after the restore is completed.

The implementation should be similar to our current MySQL implementation, and use systemctl to restart the services (mongod, pbm-agent).

Out of Scope

Docker installations of MongoDB.

Doc: 

• Update / eliminate limitation  about need to restart MongoDB in this case