OIDC backchannel logout follows redirects

### Describe the bug

The OIDC spec for the back channel logout says the response code for a request can be `200`, `204`, or `400`.

However if the response code is `301` with a `Location` header it will follow this redirect.

The spec doesn't explicitly disallow following redirects, but it feels wrong to do so. Since this would turn a POST request into a GET request.
The spec also doesn't explicitly allow following redirects.

[Spec](https://openid.net/specs/openid-connect-backchannel-1_0.html#BCResponse)

### How to reproduce

1. Create an OIDC connect provider + application.
2. Setup an app that uses this OIDC application, create a backchannel logout route that returns a `301` redirect.
3. Setup a backchannel logout url in the provider.
4. Log into the application
5. Log out of the main Authentik dashboard to trigger a backchannel logout.
6. Authentik will follow the redirect.

### Expected behavior

The backchannel logout task call should be marked as having an error and not follow the redirect.

### Screenshots

_No response_

### Additional context

_No response_

### Deployment Method

Docker

### Version

2025.10.3

### Relevant log output

```shell

```