[ci] Set default ACR in UpgrateVersion/PR/official pipeline.

.azure-pipelines/official-build.yml

@@ -18,9 +18,20 @@ schedules:
     - 201911
     - 201811
 
+resources:
+  repositories:
+  - repository: buildimage
+    type: github
+    name: Azure/sonic-buildimage
+    ref: master
+    endpoint: build
+
 trigger: none
 pr: none
 
+variables:
+- template: .azure-pipelines/template-variables.yml@buildimage
+
 stages:
 - stage: Build
   pool: sonicbld

azure-pipelines.yml

@@ -30,6 +30,14 @@ resources:
     type: github
     name: Azure/sonic-mgmt
     endpoint: build
+  - repository: buildimage
+    type: github
+    name: Azure/sonic-buildimage
+    endpoint: build
+    ref: master
+
+variables:
+- template: .azure-pipelines/template-variables.yml@buildimage
 
 stages:
 - stage: Build