Update prepare-pipelines.yml (Azure#19700)

Author: Konrad Jamrozik

eng/pipelines/prepare-pipelines.yml

@@ -1,7 +1,7 @@
 trigger: none
 
 extends:
-  template: /eng/common/pipelines/templates/steps/prepare-pipelines.yml
+  template: /eng/common/pipelines/templates/jobs/prepare-pipelines.yml
   parameters:
     Repository: $(Build.Repository.Name)
     Prefix: go