www/gitlab: security and bugfix update to 17.8.4

Changes: https://about.gitlab.com/releases/2025/02/26/patch-release-gitlab-17-9-1-released/
Security: 8fb9101e-f58a-11ef-b4e4-2cf05da270f3
(cherry picked from commit 28ff3140ed7e72c6b432459c831c47577530a38b)