test_runner: delegate split message to reporter
Delegate stdout formatting (splitting message) to reporter
Refs: https://github.com/nodejs/node/pull/48045#discussion_r1196630748
TODO:
- Update commit message
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Delegate stdout formatting (splitting message) to reporter
Refs: https://github.com/nodejs/node/pull/48045#discussion_r1196630748
TODO: