leave base medusa schema only in modules

packages/core/modules-sdk/src/medusa-app.ts

@@ -231,14 +231,8 @@ function isMedusaModule(mod) {
 }
 
 function cleanAndMergeSchema(loadedSchema) {
-  const defaultMedusaSchema = `
+  const { schema: cleanedSchema, notFound } =
-    scalar DateTime
+    GraphQLUtils.cleanGraphQLSchema(loadedSchema)
-    scalar JSON
-    directive @enumValue(value: String) on ENUM_VALUE
-  `
-  const { schema: cleanedSchema, notFound } = GraphQLUtils.cleanGraphQLSchema(
-    defaultMedusaSchema + loadedSchema
-  )
   const mergedSchema = GraphQLUtils.mergeTypeDefs(cleanedSchema)
   return {
     schema: GraphQLUtils.makeExecutableSchema({ typeDefs: mergedSchema }),