Only subscribe to identity updates if the room is encrypted. (#3414)

ElementX/Sources/Services/Room/JoinedRoomProxy.swift

@@ -200,7 +200,9 @@ class JoinedRoomProxy: JoinedRoomProxyProtocol {
         
         subscribeToRoomInfoUpdates()
         
-        subscribeToIdentityStatusChanges()
+        if isEncrypted {
+            subscribeToIdentityStatusChanges()
+        }
         
         subscribeToTypingNotifications()
     }