Fix rollout_issue_url in combined_menu.yml

config/feature_flags/development/combined_menu.yml

 ---
 name: combined_menu
 introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/56249
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/321904
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/324086
 milestone: '13.10'
 type: development
 group: group::editor