Rename CI/CD Sidekiq queues
This is a follow-up on https://gitlab.com/gitlab-com/infrastructure/issues/2210#note_34686647.
We would like to rename CI/CD Sidekiq queues to better reflect what is being done in a queue, and to improve background processing.
We want to create a new queue, called pipeline_processing
that would be realtime, and move there Sidekiq workers that are meant to update build / pipeline statuses and process a pipeline.