[BUG] Wrong error message format when forbidden or not found

[svituz]

Describe the bug

When trying to access negotiations for another user, the Forbidden response structure is wrong. The same happens when acccessing a negotiations that doesn't exist

How to reproduce

• In dev environment, using postman, get a token for "researcher" (user 1)
• Try to access negotiations of user 2 (i.e., GET /api/v3/users/2/negotiations)

What happens The response contains the following JSON structure

{
    "timestamp": "2024-03-21",
    "status": 403,
    "error": "Forbidden",
    "trace": ".....<very long stack trace>",
    "message": "403 FORBIDDEN",
    "path": "/api/v3/users/2/negotiations"
}

What should happen The response should have the common error structure

{
  "type": "",
  "title": "",
  "details": "",
  "status": ""
}

NOTE To reproduce the bug for Unauthorized use the endpoint /api/v3/negotiations/unkn