Fix automute

bbb-echotest-autojoin.user.js

@@ -48,6 +48,9 @@ function isMuted() {
 
         getEchotestAcceptButton().click();
 
+        // Directly after connecting it might be muted for a short time before unmuting
+        await sleep(500);
+
         // Ensure that the microphone is muted after joining
         while (isMuted() != true) {
             getMuteButton().click();