Merge branch 'maintenance/ff-yml' into 'master'

Update some Source Code feature flag yml files

See merge request gitlab-org/gitlab!45332

config/feature_flags/development/global_default_branch_name.yml

 ---
 name: global_default_branch_name
-introduced_by_url: 
-rollout_issue_url: 
-group: 
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/35269
+rollout_issue_url:
+group: group::source code
 type: development
 default_enabled: true

config/feature_flags/development/mr_commit_neighbor_nav.yml

 ---
 name: mr_commit_neighbor_nav
-introduced_by_url: 
-rollout_issue_url: 
-group: 
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/28596
+rollout_issue_url:
+group: group::source code
 type: development
 default_enabled: true