TaskCanceledException when host scaling down

We're seeing TaskCancelledExceptions almost daily in our Function Apps. They always seem to happen during scaling down, because when checking the logs for the host instance it's always in connection with the host shutting down that these exceptions are thrown and logged as error logs.

Stack trace of the exception

```
System.Threading.Tasks.TaskCanceledException:
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.Azure.WebJobs.Script.Description.WorkerFunctionInvoker+d__9.MoveNext (Microsoft.Azure.WebJobs.Script, Version=4.19.0.0, Culture=neutral, PublicKeyToken=null: /_/src/WebJobs.Script/Description/Workers/WorkerFunctionInvoker.cs:96)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.Azure.WebJobs.Script.Description.FunctionInvokerBase+d__24.MoveNext (Microsoft.Azure.WebJobs.Script, Version=4.19.0.0, Culture=neutral, PublicKeyToken=null: /_/src/WebJobs.Script/Description/FunctionInvokerBase.cs:82)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.Azure.WebJobs.Script.Description.FunctionGenerator+d__3`1.MoveNext (Microsoft.Azure.WebJobs.Script, Version=4.19.0.0, Culture=neutral, PublicKeyToken=null: /_/src/WebJobs.Script/Description/FunctionGenerator.cs:225)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.Azure.WebJobs.Host.Executors.FunctionInvoker`2+d__10.MoveNext (Microsoft.Azure.WebJobs.Host, Version=3.0.36.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35: C:\projects\azure-webjobs-sdk-rqm4t\src\Microsoft.Azure.WebJobs.Host\Executors\FunctionInvoker.cs:52)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.Azure.WebJobs.Host.Executors.FunctionExecutor+d__33.MoveNext (Microsoft.Azure.WebJobs.Host, Version=3.0.36.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35: C:\projects\azure-webjobs-sdk-rqm4t\src\Microsoft.Azure.WebJobs.Host\Executors\FunctionExecutor.cs:581)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.Azure.WebJobs.Host.Executors.FunctionExecutor+d__32.MoveNext (Microsoft.Azure.WebJobs.Host, Version=3.0.36.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35: C:\projects\azure-webjobs-sdk-rqm4t\src\Microsoft.Azure.WebJobs.Host\Executors\FunctionExecutor.cs:527)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.GetResult (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.Azure.WebJobs.Host.Executors.FunctionExecutor+d__26.MoveNext (Microsoft.Azure.WebJobs.Host, Version=3.0.36.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35: C:\projects\azure-webjobs-sdk-rqm4t\src\Microsoft.Azure.WebJobs.Host\Executors\FunctionExecutor.cs:306)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.Azure.WebJobs.Host.Executors.FunctionExecutor+d__26.MoveNext (Microsoft.Azure.WebJobs.Host, Version=3.0.36.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35: C:\projects\azure-webjobs-sdk-rqm4t\src\Microsoft.Azure.WebJobs.Host\Executors\FunctionExecutor.cs:352)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.Azure.WebJobs.Host.Executors.FunctionExecutor+d__18.MoveNext (Microsoft.Azure.WebJobs.Host, Version=3.0.36.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35: C:\projects\azure-webjobs-sdk-rqm4t\src\Microsoft.Azure.WebJobs.Host\Executors\FunctionExecutor.cs:108)
```

#### Investigative information

Please provide the following:

- Timestamp: 2023-05-15T05:19:18.2031337Z
- Function App version: azurefunctions: 4.19.0.20414
- Function App name: prod-function-riefeuitxdkme
- Function name(s) (as appropriate): Functions.VideoSourceListener
- Invocation ID: d70a09d7-c7ea-4e47-bc46-44048be7d010
- Region: northeurope

#### Repro steps

We don't know how to reliably reproduce this error because it happens when a function app is handling a request during scaling down. We can see it in both our function app that is using a ServiceBusTrigger and a HttpTrigger.

#### Expected behavior
More graceful shutdown that doesn't include logging errors all the way to the user. We have no control over the logs apart from filtering them since we never reach our code. And filtering TaskCanceledException logs doesn't seem like the correct solution since it might have merit when it happens outside of scaling down.

We expect the function app to handle scaling down in a better way and not like it was an unexpected event.

#### Actual behavior
Function app is told to scale down and cancels the requests it's currently handling and logs errors when it should be expected behaviour and not warrant an error log. We've also seen cases where a function app is starting and then gets canceled instantly during the first request it's handling. In this case, why is the function app even started if it's just going to be shutdown immediatly?

#### Known workarounds
No known workarounds, except maybe filtering out the logs which is a really bad solution.

#### Related information

Provide any related information
We're using .NET 7, with a few different functions. We're seeing this issue using ServiceBusTrigger and HttpTrigger bindings.

Start with the stack-trace locations in src/WebJobs.Script/Description/Workers/WorkerFunctionInvoker.cs, FunctionInvokerBase.cs, and FunctionGenerator.cs, then trace cancellation through FunctionExecutor.cs. No test or reliable reproduction is provided; the desired outcome is for expected cancellation during host scale-down to avoid being logged as an error while preserving meaningful cancellation errors in other cases.

Written by the indexing model from the issue text.