Fix Slack pipeline message by API
Pipelines triggered from API don't have a corresponding user, so we show that it's from API, same as from the web UI
Closes #25609 (closed)
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Pipelines triggered from API don't have a corresponding user, so we show that it's from API, same as from the web UI
Closes #25609 (closed)