Broker-mode: when key does not match the signature, a "invalidFederatedIdentityActionMessage" is reported

[lagess]

When the WS-Fed module is used in the broker-mode of Keycloak, the signature of the assertion can be checked. When there is a mismatch of the key htat was used for signing and the key that is used to verify the signature, a weird "invalidFederatedIdentityActionMessage" is reported by Keycloak.