WaitForCompletion scope is not included in the LowLevelFuncOperation

[pshao25]

We have below code (full version):

Operation<BinaryData> result = await new DPGClient(Key, host, null).LroAsync(WaitUntil.Started, "raw");
await result.WaitForCompletionAsync();

According to #2233 (comment):

Expected behavior: we should have scope DPGClient.Lro.WaitForCompletion
Actual behavior: now we have scope DPGClient.Lro.UpdateStatus

Root cause:
We return LowLevelFuncOperation which has OperationInternalBase inside with only _updateStatusScopeName (no _waitForCompletionScopeName as what ConvertOperation does)