Track shared runners duration when job completes

What does this MR do and why?

Related to #254231 (closed)

In this MR we introduce a FF ci_always_track_shared_runners_usage that enables tracking of shared_runners_duration when a job completes.

Today when a job completes we track the amount of CI minutes consumed as job.duration * runner cost_factor. Until this MR we only tracked amount_used but for old public projects we currently use a cost_factor: 0 which means that we don't count CI minutes consumption in this scenario. However, we would like to know how long the namespace used shared runners for, regardless of the CI minutes billing. This is why we added tracking of shared_runners_duration separately from CI minutes even when CI minutes consumption is 0.

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

@@ -6,6 +6,22 @@ class UpdateBuildMinutesService < BaseService
       # Calculates consumption and updates the project and namespace statistics(legacy)
       # or ProjectMonthlyUsage and NamespaceMonthlyUsage(not legacy) based on the passed build.
       def execute(build)
+        if Feature.enabled?(:ci_always_track_shared_runners_usage, build.project, default_enabled: :yaml)
+          return unless build.complete?
+          return unless build.duration&.positive?
+          return unless build.shared_runner_build?
+
+          ci_minutes_consumed = ::Gitlab::Ci::Minutes::BuildConsumption.new(build, build.duration).amount
+
+          update_usage(build, ci_minutes_consumed)
+        else
+          legacy_update_minutes(build)
+        end
+      end
+
+      private
+
+      def legacy_update_minutes(build)
         return unless build.cost_factor_enabled?
         return unless build.complete?
         return unless build.duration&.positive?
@@ -14,13 +30,12 @@ def execute(build)
 
         return unless consumption > 0
 
-        update_minutes(consumption, build)
+        ::Ci::Minutes::UpdateProjectAndNamespaceUsageWorker.perform_async(consumption, project.id, namespace.id, build.id)
       end
 
-      private
-
-      def update_minutes(consumption, build)
-        ::Ci::Minutes::UpdateProjectAndNamespaceUsageWorker.perform_async(consumption, project.id, namespace.id, build.id)
+      def update_usage(build, ci_minutes_consumed)
+        ::Ci::Minutes::UpdateProjectAndNamespaceUsageWorker
+          .perform_async(ci_minutes_consumed, project.id, namespace.id, build.id, { duration: build.duration })
       end
 
       def namespace