Authorization: read access to private project with public RPM repository

For RPM pull package endpoint, it should be possible to pass the next spec condition:

context 'with access to package registry for everyone' do
  let(:headers) { {} }

  before do
    project.update!(visibility_level: Gitlab::VisibilityLevel::PRIVATE)
    project.project_feature.update!(package_registry_access_level: ProjectFeature::PUBLIC)
  end

  it_behaves_like 'returning response status', :success
end

Add such spec and add changes to RPM authorisation to pass conditions.