[BUG] New implementation of "nullable" decreases the accuracy of ajv errors.
### Describe the bug

The new implementation of "Nullable" prevents the developer/API client to capitalize on the AJV errors as all possible format validation errors are returned.

### To Reproduce

1. Fetch https://github.com/Bugslive/nullable
2. Install package with `npm install`
3. Start the app with `npm start`
4. Send POST request to `http://127.0.0.1:8083/rest/nullable` with body `{"name": "toto", "description": "aaaaaaaaaaaa"}`
5. Observe the answer and especially the number of errors (3 errors).
6. Compare with error with v7.75.3

### Expected behavior

The expected number of error is 1, and error to be:
    {
      "instancePath": "/description",
      "schemaPath": "#/properties/description/maxLength",
      "keyword": "maxLength",
      "params": {
        "limit": 10
      },
      "message": "must NOT have more than 10 characters",
      "data": "aaaaaaaaaaaa",
      "modelName": "ExampleModel",
      "dataPath": ".description",
      "requestPath": "body"
    }

### Code snippets

_No response_

### Repository URL example

https://github.com/Bugslive/nullable

### OS

macOS

### Node version

Node v22.4.1

### Library version

v7.75.4

### Additional context

_No response_