`Gitlab::Geo::JobArtifactUploader` can inherit from the wrong `FileUploader` class depending on load order

See build failure: https://dev.gitlab.org/gitlab/gitlab-ee/-/jobs/2187313

This is reproducible locally with the following command:

bundle exec rspec spec/uploaders/ spec/ee/spec/lib/gitlab/geo/job_artifact_uploader_spec.rb

I think we need to be more specific in our inheritance, i.e., class JobArtifactUploader < ::Gitlab::Geo::FileUploader