InvalidOperationException with message "Block is full"

Hi guys,

First of all, thank you very much for the wonderful work ! Orleans is so useful and dev time saving !
That said, my team and I found 5.2K occurences of a `System.InvalidOperationException` with this error message : "Block is full"

Here is the stack trace:

```
System.InvalidOperationException:
at Orleans.Providers.Streams.Common.PooledQueueCache.Add (OrleansProviders, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null)
at Orleans.ServiceBus.Providers.EventHubQueueCache.Add (Orleans.Streaming.EventHubs, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null)
at Orleans.ServiceBus.Providers.EventHubAdapterReceiver+d__22.MoveNext (Orleans.Streaming.EventHubs, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null)
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 Orleans.Streams.PersistentStreamPullingAgent+d__37.MoveNext (Orleans.Runtime, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null)
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 Orleans.Internal.AsyncExecutorWithRetries+d__4`1.MoveNext (Orleans.Core, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Orleans.Internal.AsyncExecutorWithRetries+d__4`1.MoveNext (Orleans.Core, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null)
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 Orleans.Streams.PersistentStreamPullingAgent+d__35.MoveNext (Orleans.Runtime, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null)
```

The formatted message was :
`Giving up reading from queue my-stream-0 after retry attempts 6`

We are using Orleans v3.5.0
We don't have an explanation why this exception has been raised or what could have triggered it.
We analyzed Orleans' code but, beside finding where it is actually raised, we could not figure out a way where this case could occur.

Do you have any idea on your side ?

N.B.: it is a repost from your Discord asked by @ReubenBond