Update message
Updates message to reflect new expected end time.
Gitlab will be upgraded from 18.2.8 to 18.9.5 Thursday evening (20260416). Expect services to be down starting 6:00PM CT (1800). See the following release notes:
Gitlab 18.3 Gitlab 18.4 Gitlab 18.5 Gitlab 18.6 Gitlab 18.7 Gitlab 18.8 Gitlab 18.9Updates message to reflect new expected end time.