Complete confirming an instance in Localtest gives Forbidden response

## Describe the bug
Not possible to complete confirm instance in localtest

## To Reproduce
Steps to reproduce the behavior:
1. Create an instance in local test
2. Retrieve app owner token
3. POST request to instance/complete endpoint
4. See error

## Expected behavior
It should be possible to complete confirm with app owner token i local test

## Additional info
```
info: Microsoft.AspNetCore.Authorization.DefaultAuthorizationService[2]
Authorization failed. Fail() was explicitly called.
info: AltinnCore.Authentication.JwtCookie.JwtCookieHandler[13]
AuthenticationScheme: JwtCookie was forbidden.
```

Start by reproducing the issue in Localtest using the listed steps: create an instance, retrieve the app owner token, and POST to the instance/complete endpoint. Investigate why authorization rejects the app owner token, then verify that completing confirmation succeeds without the Forbidden response.

Written by the indexing model from the issue text.