fix(watcher): set default timeout for watcher service

- Changed the `WatcherTimeout` property to provide a default value of 1800 seconds if no timeout is specified.
- Updated cancellation token logic to use the new `WatcherTimeout` value, ensuring consistent behavior in resource watching operations.

Author: winromulus

src/ES.Kubernetes.Reflector/Core/Watchers/WatcherBackgroundService.cs

@@ -20,7 +20,7 @@ public abstract class WatcherBackgroundService<TResource, TResourceList>(
     protected readonly ILogger Logger = logger;
     protected readonly IMediator Mediator = mediator;
 
-    protected int? WatcherTimeout => options.CurrentValue.Watcher?.Timeout;
+    protected int WatcherTimeout => options.CurrentValue.Watcher?.Timeout ?? 1800;
 
     protected override async Task ExecuteAsync(CancellationToken stoppingToken)
     {
@@ -37,13 +37,13 @@ protected override async Task ExecuteAsync(CancellationToken stoppingToken)
             {
                 Logger.LogInformation("Requesting {type} resources", typeof(TResource).Name);
 
-                using var delayTokenCts = new CancellationTokenSource(TimeSpan.FromSeconds(WatcherTimeout ?? 900));
-                using var sleepCts =
-                    CancellationTokenSource.CreateLinkedTokenSource(stoppingToken, delayTokenCts.Token);
+
+                using var absoluteTimeoutCts = new CancellationTokenSource(TimeSpan.FromSeconds(WatcherTimeout + 3));
+                using var cancellationCts = CancellationTokenSource.CreateLinkedTokenSource(stoppingToken, absoluteTimeoutCts.Token);
                 using var client = scope.ServiceProvider.GetRequiredService<IKubernetes>();
 
                 using var watcher = OnGetWatcher(client, stoppingToken);
-                var watchList = watcher.WatchAsync<TResource, TResourceList>(cancellationToken: sleepCts.Token);
+                var watchList = watcher.WatchAsync<TResource, TResourceList>(cancellationToken: cancellationCts.Token);
 
                 await foreach (var (type, item) in watchList)
                     await Mediator.Publish(new WatcherEvent