Update validation test according to latest PBR block changes

tests/validation/config.json

@@ -79,7 +79,7 @@
         },    
         {
             "title": "Node material PBR 1",
-            "playgroundId": "#D8AK3Z#15",
+            "playgroundId": "#D8AK3Z#17",
             "referenceImage": "node-material-pbr-1.png"
         },    
         {