MicroCloud should fetch local services on demand

When the MicroCloud daemons comes up, it uses the content interfaces in order to check for the presence of MicroCeph and MicroOVN.
Once this is check is done, it enters a loop checking for their presence every second.
If one of the services is detected, the internal map of services on the daemon `s.Services` gets updated so that those can be used later down in the code.

Instead of entering a continuous loop, MicroCloud should only ever fetch those services on demand if requested.
Caching the presence of the service might not be a good idea to cope with situations in which a services gets removed after MicroCloud is already started and learned about the presence of this service.