stop forwarding `json.tracked_items_encoded` in rails and sidekiq to ES (PubSub)

This came up when working on: https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/10094

json.tracked_items_encoded fields added to our structured logging? They seem to be adding quite a bit of extra log volume, and they’re not in a format that’s particularly useful to ELK