Update GraphqlExtractor return value to be original hash

What does this MR do?

This MR updates Bulk Import's GraphqlExtractor to return original hash instead of wrapping it in an Enumerator.

A bug has been introduced in !50951 (merged) with addition of Array.wrap, which caused return value of Extractor, an enumerator, to be wrapped, which caused exception to be raised in HashKeyDigger https://gitlab.com/gitlab-org/gitlab/blob/georgekoltsov/fix-bulk-import-graphql-extractor/lib/bulk_imports/common/transformers/hash_key_digger.rb#L12-11 since data was no longer Hash.

Mentions #283945 (closed)

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team