Respect namespaces with unlimited minutes

Internal Gitlab owned namespaces only (example: gitlab-org) have unlimited
minutes. Fix a bug where the builds were dropped when mintues were set
to 0 i.e. unlimited

Changelog: fixed

app/models/namespace.rb

@@ -274,6 +274,11 @@ class Namespace < ApplicationRecord
     projects.with_shared_runners.any?
   end
 
+  # Internal Gitlab owned namespaces only (example: gitlab-org)
+  def unlimited_minutes?
+    shared_runners_minutes_limit == 0
+  end
+
   def user_ids_for_project_authorizations
     [owner_id]
   end

ee/app/services/ci/minutes/track_live_consumption_service.rb

@@ -77,6 +77,8 @@ module Ci
           ServiceResponse.error(message: 'Feature not enabled')
         elsif !build.running?
           ServiceResponse.error(message: 'Build is not running')
+        elsif root_namespace.unlimited_minutes?
+          ServiceResponse.error(message: 'Namespace has unlimited minutes')
         elsif !build.cost_factor_enabled?
           ServiceResponse.error(message: 'Cost factor not enabled for build')
         else

ee/spec/services/ci/minutes/track_live_consumption_service_spec.rb

@@ -80,6 +80,14 @@ RSpec.describe Ci::Minutes::TrackLiveConsumptionService do
       it_behaves_like 'returns early', 'Cost factor not enabled for build'
     end
 
+    context 'when namespace has unlimited minutes' do
+      before do
+        namespace.update!(shared_runners_minutes_limit: 0)
+      end
+
+      it_behaves_like 'returns early', 'Namespace has unlimited minutes'
+    end
+
     context 'when build has not been tracked recently' do
       it 'considers the current consumption as zero' do
         response = subject