Retry build files task in cg.yml (#14043)

* Retry build files.

Author: sean-mcmanus

Build/cg/cg.yml

@@ -98,9 +98,20 @@ extends:
         - script: mkdir $(Build.ArtifactStagingDirectory)\Extension
           displayName: Create Extension Staging Directory
 
-        - script: yarn run vsix-prepublish
+        - task: Bash@3
           displayName: Build files
-          workingDirectory: $(Build.SourcesDirectory)\Extension
+          inputs:
+            targetType: 'inline'
+            script: |
+              export SRC_DIR=$(echo $BUILD_SOURCESDIRECTORY | sed 's|\\|/|g')
+              cd "$SRC_DIR/Extension"
+              yarn run vsix-prepublish
+              if [ $? -ne 0 ]; then
+                echo "yarn run vsix-prepublish failed, sleeping for 30s before retrying..."
+                sleep 30
+                exit 1
+              fi
+          retryCountOnTaskFailure: 3
 
         - script: |
             cd $(Build.SourcesDirectory)\Extension