I noticed while looking at scale test metrics that we don't always
report a useful path in the API request metrics.

There are a lot of requests with path `/*`. I chased this problem to the
workspace proxy, where we mount a the proxy router as a child of a
"root" router to support some high level endpoints like `latency-check`.
Because we query the path from the Chi route context in the prometheus
middleware _before_ the request is actually handled, we can have a
partially resolved pattern match only corresponding to the root router.
The fix is to always re-resolve the path, rather than accept a partially
resolved path.