If replication has not caught up properly on the secondary,
it was possible for a primary Geo node to attempt an update
of the GeoNodeStatus entry with a `nil` ID, resulting
in an Error 500.

We handle this in two ways:

1. On the primary, ignore `id` and other unknown attributes.
2. On the secondary, never send `id`.

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/8966