PLT-2777 hide create account when not an open server (#2872)

webapp/components/login/login.jsx

@@ -342,7 +342,9 @@ export default class Login extends React.Component {
             );
         }
 
-        const userSignUp = (
+        var userSignUp;
+        if (global.window.mm_config.EnableOpenServer === 'true') {
+            userSignUp = (
                 <div>
                     <span>
                         <FormattedMessage
@@ -361,6 +363,7 @@ export default class Login extends React.Component {
                     </span>
                 </div>
             );
+        }
 
         let forgotPassword;
         if (usernameSigninEnabled || emailSigninEnabled) {