www/gitlab: security and patch update to 18.8.4

also mark gitaly to not work on i386, see also:
https://gitlab.com/gitlab-org/gitaly/-/merge_requests/8309#note_3075944887

Changes: https://about.gitlab.com/releases/2026/02/10/patch-release-gitlab-18-8-4-released/
(cherry picked from commit 209a937925388638d33b84ef2af3c8a040f26138)