Docs: add notice for `docker login` about concurrency
If someone allows to run several jobs in parallel on gitlab-ci runner, it could eventually fail because of docker login credentials overriden due race-condition between jobs.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
If someone allows to run several jobs in parallel on gitlab-ci runner, it could eventually fail because of docker login credentials overriden due race-condition between jobs.