Remove group_merge_request_approval_settings feature flag from codebase

Problem to solve

Feature flags become unnecessary after we change them to default to on. In #285410 (closed) (%14.5) we changed the group_merge_request_approval_settings feature flag to default to on.

Prposal

In 14.6 (or later) we should cleanup and remove this flag from the codebase.

Implementation guide

These are most (all?) of the files that need to be changed:

• ee/app/models/ee/project.rb
• ee/app/policies/ee/group_policy.rb
• ee/app/policies/ee/project_policy.rb
• ee/app/controllers/ee/projects_controller.rb
• ee/app/helpers/ee/projects_helper.rb
• ee/app/helpers/groups/merge_request_approval_settings_helper.rb
• ee/config/feature_flags/development/group_merge_request_approval_settings_feature_flag.yml:name
• ee/spec/features/projects/audit_events_spec.rb
• ee/spec/features/groups/group_settings_spec.rb
• ee/spec/models/project_spec.rb stub_feature_flags(group_merge_request_approval_settings_feature_flag
• ee/spec/models/approval_state_spec.rb
• ee/spec/requests/api/merge_request_approval_settings_spec.rb
• ee/spec/helpers/projects_helper_spec.rb
• ee/lib/api/merge_request_approval_settings.rb
• doc/user/group/index.md
• doc/user/project/merge_requests/approvals/settings.md

This list was generated using:

• grep -R group_merge_request_approval_settings app
• grep -R group_merge_request_approval_settings doc
• grep -R group_merge_request_approval_settings config
• grep -R group_merge_request_approval_settings ee
• grep -R group_merge_request_approval_settings spec