Callback required twice

[martinkearn]

The function seems to need the callback URL to be called twice in order to break eth while loop.

If you call it once, you will get 202/Accepted but the loop will continue and eventually reach the max retry count with a status of timedout.

However if you call it twice, the second call will break the loop and complete the function with a status of calledback.

[martinkearn]

Needed to add using (await context.LockAsync(attemptCounterEntityId)) around the callback