API access token generation fails after Upgrade

[Theodotos Andreou]

Hello team

We are trying to generate a rw access token (for adding users, groups, etc). In previous version (19.x) this used to work:

```

    $ curl -X POST -s --location https://kc-test.example.com/auth/realms/master/protocol/openid-connect/token --header 'Content-Type: application/x-www-form-urlencoded' --header 'Authorization: Basic BASE64usernamePass' --data-urlencode grant_type=password --data-urlencode client_id=admin-cli --data-urlencode username=admin --data-urlencode password=TestKCAdminPass

    {"error":"unauthorized_client","error_description":"Invalid client or Invalid client credentials"}
```

This stopped working after the upgrade to 24.0.4.

Has anything changed in the API call?

[Björn Pedersen]

Passing the username and password twice seems fishy, check how it is done here:

 https://www.keycloak.org/docs/latest/server_development/index.html#examples-of-using-curl