Persist the data after PaymentServiceProviderServiceInterface::start()

It currrently only persists the data before calling out to the connector,
this means the connector payment changes won't get saved to the DB
(it currently doesn't do any changes, but we want to update the status
in there in the future)

src/Service/PaymentService.php

@@ -424,6 +424,9 @@ public function startPayAction(StartPayAction $startPayAction): StartResponseInt
 
         $paymentPersistence->setStartedAt($now);
 
+        $paymentServiceProvider = $this->paymentServiceProviderService->getByPaymentContract($paymentContract);
+        $startResponse = $paymentServiceProvider->start($paymentPersistence);
+
         try {
             $this->em->persist($paymentPersistence);
             $this->em->flush();
@@ -432,9 +435,6 @@ public function startPayAction(StartPayAction $startPayAction): StartResponseInt
             throw new ApiError(Response::HTTP_INTERNAL_SERVER_ERROR, 'Payment could not be updated!');
         }
 
-        $paymentServiceProvider = $this->paymentServiceProviderService->getByPaymentContract($paymentContract);
-        $startResponse = $paymentServiceProvider->start($paymentPersistence);
-
         return $startResponse;
     }