Fix/mico#871 status endpoint

[davidkopp]

Description

The status endpoint should only return the service instances, that are actually deployed (availableReplicas > 0) or at least should be deployed (requestedReplicas > 0).

• [ ] this PR contains breaking changes!

Resolves / is related to

Closes #871

What is affected by this PR

• [x] Backend
  • [ ] Kubernetes logic
  • [ ] Domain model
• [x] API
  • [x] discussed changes in the team / informed the team about changes
  • [ ] updated insertTestValues.sh and Postman Collections are updated
• [ ] Frontend
  • [ ] Ensure that it is compilable for production (npm run build -- --prod)
• [ ] Documentation

Checklist

• [x] Ensure that new source files include the license header
• [x] Ensure JavaDoc is up to date