Fix coverage with new decoupled backend

[vkotronis]

Describe the bug
current convert_coverage.sh script:

#!/bin/sh
docker cp backend:/root/core/.coverage .coverage
sed -i "s;/root/core/;${PWD}/backend/core/;g" .coverage
coverage xml --rcfile testing/.coveragerc

We need to account for the new modules, which are under
backend-services

Structure is as follows:

backend-services/
├── service
│   ├── AUTHORS.md
│   ├── core
│   │   ├── service.py
│   │   └── __init__.py
│   ├── Dockerfile
│   ├── entrypoint
│   ├── LICENSE
│   ├── Makefile
│   ├── requirements.txt
│   └── wait-for
..........

where service = [autoignore, autostarter, configuration, database, detection, fileobserver, mitigation, notifier, prefixtree]

Affected Component(s)

• Back-End (Database, Microservices, Containers, etc)
• Front-End (Flask, API, etc)
• Docs
• Build System

Expected behavior
Backend services need to be properly covered.

[vkotronis]

@slowr should I move this to another release?