Move vars to env in azure-pipelines.yml

azure-pipelines.yml

@@ -2,11 +2,9 @@ pool:
   vmImage: 'Ubuntu 16.04'
 
 steps:
-- script: docker login $ACR_REGISTRY -u $ACR_USER -p "$ACR_PASSWORD"
+- script: docker login $(ACR_USER) -u $(ACR_REGISTRY) -p $pswd
   env:
-    ACR_REGISTRY: $(ACR_REGISTRY)
-    ACR_USER: $(ACR_USER)
-    ACR_PASSWORD: $(ACR_PASSWORD)
+    pswd: $(ACR_PASSWORD)
   displayName: Docker Login
 - script: docker build . -t "$(DOCKER_IMAGE_NAME)"
   displayName: Docker Build