Update GraphqlExtractor return value to be original hash

- A bug was introduced in
  https://gitlab.com/gitlab-org/gitlab/-/merge_requests/50951
  with addition of `Array.wrap`, which caused return value of
  `GraphqlExtractor`, an enumerator, to be wrapped in an Array,
  which caused exception to be raised in `HashKeyDigger`
- Update return value of `GraphqlExtractor` to be original hash
  instead of wrapping it in an enumerator, there is no need for it

changelogs/unreleased/georgekoltsov-fix-bulk-import-graphql-extractor.yml

+---
+title: Update GraphqlExtractor return value to be original hash
+merge_request: 51596
+author:
+type: fixed

lib/bulk_imports/common/extractors/graphql_extractor.rb

@@ -11,14 +11,10 @@ module BulkImports
         def extract(context)
           client = graphql_client(context)
 
-          Enumerator.new do |yielder|
-            result = client.execute(
-              client.parse(query.to_s),
-              query.variables(context.entity)
-            )
-
-            yielder << result.original_hash.deep_dup
-          end
+          client.execute(
+            client.parse(query.to_s),
+            query.variables(context.entity)
+          ).original_hash.deep_dup
         end
 
         private

spec/lib/bulk_imports/common/extractors/graphql_extractor_spec.rb

@@ -27,11 +27,8 @@ RSpec.describe BulkImports::Common::Extractors::GraphqlExtractor do
       allow(graphql_client).to receive(:execute).and_return(response)
     end
 
-    it 'returns an enumerator with fetched results' do
-      response = subject.extract(context)
-
-      expect(response).to be_instance_of(Enumerator)
-      expect(response.first).to eq({ foo: :bar })
+    it 'returns original hash' do
+      expect(subject.extract(context)).to eq({ foo: :bar })
     end
   end