Authentik 2025.10.3 - Read-only field - Is 'allow blank' really working?

### Describe the bug

This morning I have seen the release of Authentik 2025.10.3.

I have seen this line within the changelog:
```
stages/prompt: set allow_blank for _read_only fields (cherry-pick [#18297](https://github.com/goauthentik/authentik/issues/18297) to version-2025.10) ([#18406](https://github.com/goauthentik/authentik/issues/18406))
```

That interests me as I need a read-only field which accept blank/empty value: for the moment I have a workaround but I expected to be able to delete it.

I updated from 2025.10.2 to 2025.10.3 but if my read-only field is not filled it does not work.

Maybe I misunderstood the patch but:
- I see no new parameter in the web interface to configure 'allow_blank'
- I see no new parameter in the API to configure 'allow_blank'
- the parameter 'Required' seems to have no effect

Is the pull #18297 really working?
Is the patch supposed to allow empty values ​​in read-only fields?

Thank you very much :-)

### How to reproduce

To avoid to reinvent the wheel, please refer to the issue [#18228](https://github.com/goauthentik/authentik/issues/18228)

### Expected behavior

Read-only field should accept empty/blank value

### Screenshots

_No response_

### Additional context

_No response_

### Deployment Method

Docker

### Version

2025.10.3

### Relevant log output

```shell

```

Start with the reproduction details in issue #18228 and review the referenced changes in issues #18297 and #18406. Confirm the behavior on Authentik 2025.10.3 using the described read-only field configuration and determine whether blank values are accepted; done means the expected behavior is clarified and the reported configuration works as intended.

Written by the indexing model from the issue text.