remove PROD supplier config

Author: nhsd-david-wass

config/suppliers/letter-variant/digitrials-aspiring.json

@@ -32,7 +32,6 @@
     "digitrials-aspiring"
   ],
   "status": "INT",
-  "supplierId": "datagraphic",
   "type": "STANDARD",
-  "volumeGroupId": "datagraphic"
+  "volumeGroupId": "volumeGroup-test3"
 }