simplified code across the app and consolidated duplicated helpers

lib/api/marianumcloud/talk/get_reactions/get_reactions.dart

@@ -1,7 +1,3 @@
-import 'package:http/http.dart' as http;
-import 'package:http/http.dart';
-
-import '../../../api_params.dart';
 import '../../nextcloud_ocs.dart';
 import '../talk_api.dart';
 import 'get_reactions_response.dart';
@@ -15,11 +11,4 @@ class GetReactions extends TalkApi<GetReactionsResponse> {
   @override
   GetReactionsResponse assemble(String raw) =>
       GetReactionsResponse.fromJson(NextcloudOcs.decode(raw));
-
-  @override
-  Future<Response>? request(
-    Uri uri,
-    ApiParams? body,
-    Map<String, String>? headers,
-  ) => http.get(uri, headers: headers);
 }