Create a method for failed_archive_counter

app/workers/ci/rescue_stale_live_trace_worker.rb

@@ -7,8 +7,6 @@ module Ci
       # Archive stale live traces which still resides in redis or database
       # This could happen when ArchiveTraceWorker sidekiq jobs were lost by receiving SIGKILL
       # More details in https://gitlab.com/gitlab-org/gitlab-ce/issues/36791
-      failed_archive_counter = Gitlab::Metrics.counter(:job_stale_live_trace_failed_archive_total, "Counter of failed archiving with stale live trace")
-
       Ci::Build.finished.with_live_trace.find_each(batch_size: 100) do |build|
         begin
           build.trace.archive!
@@ -18,5 +16,11 @@ module Ci
         end
       end
     end
+
+    private
+
+    def failed_archive_counter
+      @failed_archive_counter ||= Gitlab::Metrics.counter(:job_trace_archive_failed_total, "Counter of failed attempts of traces archiving")
+    end
   end
 end