API fix for non UTF-8 data

What does this MR do?

This should fix #35942 (closed) when trying to represent non UTF-8 data in JSON. There are some diff that treated as text when they are binary.

This fix will fake the standard binary message instead of dumping binary data.

Are there points in the code the reviewer needs to double check?

Should I add API level tests for the specific gitlab-test commit? Where are those located?

Why was this MR needed?

Calling the api endpoint caused a 500 error.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together

What are the relevant issue numbers?