Check for both folder and folder/ as hdi_isfolder blobs

[adreed-msft]

The old implementation was designed against an HNS account, not a FNS account, and was almost always tested against HNS.

On HNS, if you were using the blob endpoint, and you listed, you wouldn't get returned folder stub blobs. You'd have to manually ping them for properties. Two things happened because of this.

1. We manually checked for folder.
2. We could schedule folder twice working against blob on FNS, because it'd now appear inside the listed items. This would cause a panic, because we'd try to deschedule a successful folder twice.

A third problem arose with certain customers, where they were following this format, but misunderstood it, and actually named their folders folder/. In this case, we'd find folder/ normally, and it'd function like expected. But the original code wasn't explicitly checking for it.

So the solution is, always ignore the folder blobs when we're sent them as list items. Always check both folder and folder/. This means we'll always catch it, even on HNS.