Fixing graphdb to mongodb

[jt-dd]

With KHaaS, rehydrating the data from the dump:

• Checking if the data is already ingested (is there at least one data with run_id / cluster present in Janusgraph)
• Checking if there is data in the MongoDB (looping over the collection to find assets with run_id / cluster)
  • If found, deleting the data, to rerun the ingestion process.

Added a system-test to simulate GRPC ingestion.