Fix the issue with verifyMssKey overriding is_approved

The verifyMssKey side effect handler was overriding the value
of is_approved when updating the state.

[MAILPOET-4633]

mailpoet/lib/API/JSON/v1/Services.php

@@ -126,7 +126,7 @@ class Services extends APIEndpoint {
     }
 
     if ($successMessage) {
-      return $this->successResponse(['message' => $successMessage, 'state' => $state]);
+      return $this->successResponse(['message' => $successMessage, 'state' => $state, 'result' => $result]);
     }
 
     switch ($state) {