Update existing CODEOWNERS tests to include multiple sections

The existing tests should be updated to include multiple CODEOWNERS sections to cover the changes in gitlab-org/gitlab#12137 (closed)

• qa/specs/features/ee/browser_ui/3_create/repository/assign_code_owners_spec.rb
• qa/specs/features/ee/browser_ui/3_create/repository/code_owners_spec.rb