Merge branch 'mk/fix-changelog-docs' into 'master'

Remove duplicate section in changelog

See merge request gitlab-org/gitlab-ee!15113

CHANGELOG.md

@@ -697,14 +697,6 @@ entry.
 - Upgrade pages to 1.5.1 to prevent gitlab api token recovery from cookie.
 
 
-## 11.11.8
-
-### Security (2 changes)
-
-- Upgrade Gitaly to 1.42.7 to prevent revision flag injection exploits.
-- Upgrade pages to 1.5.1 to prevent gitlab api token recovery from cookie.
-
-
 ## 11.11.7
 
 ### Security (9 changes)