Make sure worker attributes are populated for mailer jobs
Coming from the https://gitlab.com/gitlab-com/gl-infra/production/-/issues/3531#note_504158767:
The mailers queue does not have a worker in the application code, instead, it's using ActionMailer::MailDeliveryJob
defined in rails.
As a result, the apdex can't be calculated for it, causing the graphs to be empty: https://dashboards.gitlab.net/d/sidekiq-queue-detail/sidekiq-queue-detail?orgId=1&var-PROMETHEUS_DS=Global&var-environment=gprd&var-stage=main&var-queue=mailers
We should make sure the ActionMailer::MailDeliveryJob
gets worker attributes populated so metrics are correctly gathered for it.
Edited by Bob Van Landuyt