Merge branch 'if-update_admin_mode_ff' into 'master'

Update admin mode feature flag details

See merge request gitlab-org/gitlab!53843

config/feature_flags/development/user_mode_in_session.yml

 ---
 name: user_mode_in_session
-introduced_by_url: 
-rollout_issue_url: 
-milestone: 
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/16981
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/321025
+milestone: 12.4
 type: development
-group: 
+group: group::access
 default_enabled: false