Sidekiq import/export logs use Rails.logger which does not use structured logging

When project exports fail we log a failure message using Rails.logger, on omnibus installations this ends up in production.log which was recently removed from central logging. It would be much better for us to have these logs in the production_json.json structured log or a separate sidekiq structured logfile.

https://gitlab.com/gitlab-org/gitlab/-/blob/8cc37ed4bc373c417d890166a2a0b5d6ee2fc8ae/lib/gitlab/import_export/shared.rb#L33

This limits visibility into failures because the from the sidekiq log we see this failed job as completed, but without any more information. see example: gitlab-com/gl-infra/scalability#200 (comment 298941726)