remove the test button from the no_command page

Students didn't read and thought they had to click it, and got confused.

Author: christianp

html/no_command.html

@@ -8,13 +8,6 @@ <h1>Numbas lockdown app</h1>
         <p>This app can be used to access Numbas exams in a controlled environment.</p>
         <p>The app is installed correctly. Click on a Numbas link in a browser to use this app.</p>
         <hr>
-        <p>You can test the launching process by clicking the button below.</p>
-        <p style="text-align: center"><button id="launch">Open the test page</button></p>
-
-        <script>
-            document.getElementById('launch').addEventListener('click', e => {
-                window.api.send('toMain', { command: 'openURL', url: 'https://www.numbas.org.uk/lockdown-app/test'});
-            });
-        </script>
+        <p>You can now close this window.</p>
     </body>
 </html>