Improve documentation for Chaos Testing Setup
Follow on from https://gitlab.com/gitlab-org/gitlab/-/merge_requests/98019#note_1156622063 to improve the documentation of how the Chaos test scenario is setup.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Follow on from https://gitlab.com/gitlab-org/gitlab/-/merge_requests/98019#note_1156622063 to improve the documentation of how the Chaos test scenario is setup.