Remove keep alive on CheckIfFediverseProvider

lib/riverpod_controllers/fediverse_server_validator_services.dart

@@ -10,8 +10,6 @@ import 'networking/network_services.dart';
 
 part 'fediverse_server_validator_services.g.dart';
 
-const _keepAliveDuration = Duration(minutes: 15);
-
 final _blueSkyData = ServerData(
   domainName: 'bsky.app',
   isFediverse: true,