updated localstore collection to global constant

lib/api/marianumcloud/talk/room/getRoomCache.dart

@@ -8,7 +8,7 @@ import 'getRoomResponse.dart';
 
 class GetRoomCache extends RequestCache<GetRoomResponse> {
   GetRoomCache({onUpdate, renew}) : super(RequestCache.cacheMinute, onUpdate, renew: renew) {
-    start('MarianumMobile', 'nc-rooms');
+    start('nc-rooms');
   }
 
   @override