Prefer higher-resolution metrics during merge
Prefer higher-resolution metrics during merge

When we get responses for a single metric that have different
resolutions, we will keep only the one that has higher resolution. This
mimics zipper's behaviour from back in the day:

    https://github.com/go-graphite/carbonzipper/blob/444288cb6/main.go#L424:L429

If we want to do something more clever, it's not clear what that should
be.

dgryski/carbonapi