GeoNodeStatus counters are allowed to have nils as a value. Does that make sense?

Based on @brodock's proposal https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/3809/diffs#note_192444898

We have to investigate if we really need that.

Example of the affected API response:

  "container_repositories_count": 3,
  "container_repositories_synced_count": nil, # this should never be nil
  "container_repositories_failed_count": nil, # this should never be nil