[ci] Fix PR validation issue involved by cherry-pick enabling ACR.

involved un-expectec lines.

azure-pipelines.yml

@@ -38,13 +38,10 @@ resources:
     ref: master
 
 variables:
-- template: .azure-pipelines/azure-pipelines-repd-build-variables.yml
 - ${{ if eq(variables['Build.Reason'], 'PullRequest') }}:
   - template: .azure-pipelines/template-variables.yml
 - ${{ else }}:
   - template: .azure-pipelines/template-variables.yml@buildimage
-- name: CACHE_MODE
-  value: rcache
 
 stages:
 - stage: Build