Removes unneeded translation. (#3217)

lang/main.json

         "focus": "Conference focus",
         "focusFail": "__component__ not available - retry in __ms__ sec",
         "grantedTo": "Moderator rights granted to __to__!",
-        "grantedToUnknown": "Moderator rights granted to $t(notify.somebody)!",
         "muted": "You have started the conversation muted.",
         "mutedTitle": "You're muted!",
         "raisedHand": "Would like to speak.",

modules/UI/UI.js

 
     const displayName = user.getDisplayName();
 
-    if (displayName) {
-        messageHandler.participantNotification(
-            displayName,
-            'notify.somebody',
-            'connected',
-            'notify.grantedTo',
-            { to: UIUtil.escapeHtml(displayName) });
-    } else {
-        messageHandler.participantNotification(
-            '',
-            'notify.somebody',
-            'connected',
-            'notify.grantedToUnknown');
-    }
+    messageHandler.participantNotification(
+        displayName,
+        'notify.somebody',
+        'connected',
+        'notify.grantedTo',
+        { to: displayName
+            ? UIUtil.escapeHtml(displayName) : '$t(notify.somebody)' });
 };
 
 /**