describe wf run includes empty information

[migmartri]

chainloop wf run describe --id [...] -o json is showing spurious information that no longer exists like id and createdAt. The reason they don't exist is because attestations are not stored in their own table anymore.

   "attestation": {        
      "id": "",                                                                
      "createdAt": "1970-01-01T00:00:00Z",  

To fix that, we need to remove the fields from the client-side struct and deprecate/remove the properties in the API proto message as well.