Reject does not work for runtime delegated signing

[tina-ahm]

Description of the bug

The user is unable to reject a signature that has been delegated through runtime delegated signing.
The documentation describes this as possible when using AdditionalActionsToDelegate.

Steps To Reproduce

1. Delegate reject action to users through ISigneeProvider (as described here).
2. In the signing step (as a user that has been delegated signing rights), click the button to reject the signature.
3. See "Request failed with status code 403"-error.

Additional Information

• https://digdir.slack.com/archives/C0760NPT2BE/p1781002346434859