Update prepare-pipelines.yml (Azure#27918)

Author: Konrad Jamrozik

eng/pipelines/prepare-pipelines.yml

@@ -1,10 +1,10 @@
 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: python
     CIConventionOptions: ''
     UPConventionOptions: '--variablegroup 58 --variablegroup 76 --variablegroup 56 --variablegroup 93'
-    TestsConventionOptions: '--variablegroup 64'
+    TestsConventionOptions: '--variablegroup 64'