Cannot populate relation to admin::user
### Node Version

22.12.0

### NPM/Yarn/PNPM Version

11.1.0

### Strapi Version

5.10.4

### Operating System

Docker/Podman/LXC

### Database

MySQL

### Javascript or Typescript

Typescript

### Reproduction URL

_No response_

### Bug Description

My collection has a field `author`, which looks like this:
```
"author": {
    "type": "relation",
    "relation": "oneToOne",
    "target": "admin::user"
}
```

Fetching via REST API and using `populate: { author: true }` does not populate the author. It doesn't return an error either, it just doesn't do anything.

I've searched through basically every Stack Overflow post and Github Issue, without finding a viable source about populating admin users through the REST API.

In the case that this is wanted behaviour, I'd also like a quick note as to why this shouldn't be possible.

### Steps to Reproduce

1. Create a content type with a relation field `author` with the target `admin::user`
2. Populate it as usual via the REST API: `populate: { author: true }`

### Expected Behavior

The expected behavior would be for STRAPI to return the admin user's details.

### Logs

```shell

```

### Code Snippets

_No response_

### Media

_No response_

### Additional information

_No response_

### Confirmation Checklist

- [x] I have checked the existing [issues](https://github.com/strapi/strapi/issues) for duplicates.
- [x] I agree to follow this project's [Code of Conduct](https://github.com/strapi/strapi/blob/develop/CODE_OF_CONDUCT.md).