[VIndex] Transient connection refused errors on startup

[mhutchinson]

On startup of at least the SumDB VIndex, there are errors logged during the first build cycle:

[main.go:152] Failed to Update index: failed to get latest checkpoint from DB: get("http://xxxxx:8000/inputlog/checkpoint"): Get "http://xxxxx:8000/inputlog/checkpoint": dial tcp xxxxxx:8000: connect: connection refused

This resolves itself after one cycle, so is minor impact. That said, it's a broken window and should be fixed. I'm pretty sure this is because the SumDB tlog-tiles proxy is brought up later than needed.