In https://gitlab.com/gitlab-org/security/gitlab-workhorse/-/merge_requests/3
we're changing Workhorse to always send empty values for unused fields,
to avoid any injected client parameters overriding them.

This causes an error in Rails because we're not checking for empty
strings in `remote_id` and attempting to store a remote file:

```
ObjectStorage::RemoteStoreError - Bad file path:
  app/uploaders/object_storage.rb:353:in `cache_remote_file!'
```