e2e fix portforward output

alfa-client/apps/alfa-e2e/Jenkinsfile

@@ -753,7 +753,7 @@ Void forwardMongoDbPort(String namespace) {
 
         def pidFile = generateMongoDbPortForwardPidFile(namespace)
 
-        sh (script: "kubectl port-forward ozg-mongodb-0 ${dbPort}:27017 -n ${namespace} & echo \$! > ${pidFile}", returnStdout: true)
+        sh "kubectl port-forward ozg-mongodb-0 ${dbPort}:27017 -n ${namespace} & echo \$! > ${pidFile}"
 
         sh "sleep 20"