Move Performance Monitoring out of beta (#5616)

* Update metrics_settings.jsx

* Update admin_sidebar.jsx

* Update en.json

webapp/components/admin_console/admin_sidebar.jsx

@@ -250,7 +250,7 @@ export default class AdminSidebar extends React.Component {
                         title={
                             <FormattedMessage
                                 id='admin.sidebar.metrics'
-                                defaultMessage='Performance Monitoring (Beta)'
+                                defaultMessage='Performance Monitoring'
                             />
                         }
                     />