Added google play testing accounts and testing environment

lib/view/pages/talk/chatMessage.dart

@@ -2,6 +2,7 @@
 import 'package:cached_network_image/cached_network_image.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_linkify/flutter_linkify.dart';
+import 'package:marianum_mobile/model/timetable/endpointData.dart';
 import 'package:url_launcher/url_launcher_string.dart';
 
 import '../../../api/marianumcloud/talk/chat/getChatResponse.dart';
@@ -48,7 +49,7 @@ class ChatMessage {
       placeholder: (context, url) {
         return const Padding(padding: EdgeInsets.all(10), child: CircularProgressIndicator());
       },
-      imageUrl: "https://cloud.marianum-fulda.de/core/preview?fileId=${file!.id}&x=100&y=-1&a=1",
+      imageUrl: "https://${EndpointData().nextcloud().full()}/core/preview?fileId=${file!.id}&x=100&y=-1&a=1",
       httpHeaders: {
         "Authorization": "Basic ${AccountData().buildHttpAuthString()}"
       },