change parallel monthly stl job count to 1 on uat

crss-dataflow-app/crss-dataflow-app-pemc-dev.yml

@@ -41,6 +41,7 @@ sftp:
     workingDirectory: /upload
 
 scheduler:
+  parallel-stl-monthly-job: 1
   job-execution-timeout-minutes:
     default: 180
     runStlReady: 480