Change data categories schema to lowercase

config/metrics/objects_schemas/collected_data_categories_schema.json

@@ -2,6 +2,6 @@
   "type": "array",
   "items": {
     "type": ["string", "null"],
-    "enum": ["Standard", "Subscription", "Operational", "Optional"]
+    "enum": ["standard", "subscription", "operational", "optional"]
   }
 }