Tidy logging and tests

boring stuff... tidy logging so that normal operation doesn't cause lots of crazy stuff even at debug level, and improves REST logging.  (we may want to move REST logging to a new file, but not done in this PR.)  and tidy tests so that they run faster.

biggest change here is a new CREATE_UNMANAGED mode for location creation, used when peeking for the frequent poll done by the GUI (now there is no debug logging as part of that)
Great to to stop this happening repeatedly! Longer term I'd like to see how we can get the information without instantiating a location at all. I think we're on the same page there, with your comment:

    // TODO should clean up how locations are stored, figuring out whether they are shared or not;
    // or maybe better, the API calls to this might just want to get the LocationSpec objects back

I wondered about us marking `CREATE_UNMANAGED` as `@Beta`, but it's in a package named "internal" anyway. If/when we fix `resolveForPeeking` to do it a different way, I'd like to delete `CREATE_UNMANAGED` (unless there are any other compelling use-cases).