Remove call to moved function

The resetting of the 2FA sso verification state was moved to the
response sent action. The caused the removal of the setVerifiedBySsoOn2faCookie
method. But the GSSP verified action still called it

src/Surfnet/StepupGateway/GatewayBundle/Controller/SecondFactorController.php

@@ -356,7 +356,6 @@ public function gssfVerifiedAction(Request $request)
 
         $context->markSecondFactorVerified();
         $this->getAuthenticationLogger()->logSecondFactorAuthentication($originalRequestId, $authenticationMode);
-        $context->setVerifiedBySsoOn2faCookie(null);
         $logger->info(sprintf(
             'Marked GSSF "%s" as verified, forwarding to Gateway controller to respond',
             $selectedSecondFactor