Fix bug in script

Author: MarcialRosales

selenium/test/authnz-msg-protocols/amqp10.js

@@ -17,7 +17,7 @@ describe('Having AMQP 1.0 protocol enabled and the following auth_backends: ' +
   let password = process.env.RABBITMQ_AMQP_PASSWORD
   let usemtls = process.env.AMQP_USE_MTLS
   let amqpClientCommand = "npm run amqp10_roundtriptest" + 
-    (usemtls ? "" : username + " " + password)
+    (usemtls ? "" : " " + username + " " + password)
 
   before(function () {
     if (backends.includes("http") && username.includes("http")) {