Don't throw from hosted services

[davidfowl]

• Shutting down the host cancels the hosted services and they shouldn't throw as a result. This reduces noise in tests as they call stop on the host on failure resulting in more exceptions than necessary

Should clean up errors like these:

fail: Microsoft.Extensions.Hosting.Internal.Host[9]
      BackgroundService failed
      System.OperationCanceledException: The operation was canceled.
         at System.Threading.Channels.AsyncOperation`1.GetResult(Int16 token)
         at System.Threading.Channels.ChannelReader`1.ReadAllAsync(CancellationToken cancellationToken)+MoveNext()
         at System.Threading.Channels.ChannelReader`1.ReadAllAsync(CancellationToken cancellationToken)+System.Threading.Tasks.Sources.IValueTaskSource<System.Boolean>.GetResult()
         at Aspire.Hosting.ApplicationModel.ResourceNotificationService.WatchAsync(CancellationToken cancellationToken)+MoveNext() in /_/src/Aspire.Hosting/ApplicationModel/ResourceNotificationService.cs:line 168
         at Aspire.Hosting.ApplicationModel.ResourceNotificationService.WatchAsync(CancellationToken cancellationToken)+MoveNext() in /_/src/Aspire.Hosting/ApplicationModel/ResourceNotificationService.cs:line 168
         at Aspire.Hosting.ApplicationModel.ResourceNotificationService.WatchAsync(CancellationToken cancellationToken)+System.Threading.Tasks.Sources.IValueTaskSource<System.Boolean>.GetResult()
         at Aspire.Hosting.Testing.ResourceLoggerForwarderService.WatchNotifications(CancellationToken cancellationToken) in /_/src/Aspire.Hosting.Testing/ResourceLoggerForwarderService.cs:line 42
         at Aspire.Hosting.Testing.ResourceLoggerForwarderService.WatchNotifications(CancellationToken cancellationToken) in /_/src/Aspire.Hosting.Testing/ResourceLoggerForwarderService.cs:line 42
         at Microsoft.Extensions.Hosting.Internal.Host.TryExecuteBackgroundServiceAsync(BackgroundService backgroundService)

and these:

BackgroundService failed
      System.OperationCanceledException: The operation was canceled.
         at System.Threading.Channels.AsyncOperation`1.GetResult(Int16 token)
         at System.Threading.Channels.ChannelReader`1.ReadAllAsync(CancellationToken cancellationToken)+MoveNext()
         at System.Threading.Channels.ChannelReader`1.ReadAllAsync(CancellationToken cancellationToken)+System.Threading.Tasks.Sources.IValueTaskSource<System.Boolean>.GetResult()
         at Aspire.Hosting.ApplicationModel.ResourceNotificationService.WatchAsync(CancellationToken cancellationToken)+MoveNext() in /_/src/Aspire.Hosting/ApplicationModel/ResourceNotificationService.cs:line 168
         at Aspire.Hosting.ApplicationModel.ResourceNotificationService.WatchAsync(CancellationToken cancellationToken)+MoveNext() in /_/src/Aspire.Hosting/ApplicationModel/ResourceNotificationService.cs:line 168
         at Aspire.Hosting.ApplicationModel.ResourceNotificationService.WatchAsync(CancellationToken cancellationToken)+System.Threading.Tasks.Sources.IValueTaskSource<System.Boolean>.GetResult()
         at Aspire.Hosting.Health.ResourceHealthCheckScheduler.ExecuteAsync(CancellationToken stoppingToken) in /_/src/Aspire.Hosting/Health/ResourceHealthCheckScheduler.cs:line 38
         at Aspire.Hosting.Health.ResourceHealthCheckScheduler.ExecuteAsync(CancellationToken stoppingToken) in /_/src/Aspire.Hosting/Health/ResourceHealthCheckScheduler.cs:line 38
         at Microsoft.Extensions.Hosting.Internal.Host.TryExecuteBackgroundServiceAsync(BackgroundService backgroundService)

Microsoft Reviewers: Open in CodeFlow

[radical]

/azp run

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