Currently, local_proxy will write an error log if it doesn't find the
config file. This is expected for startup, so it's just noise. It is an
error if we do receive an explicit SIGHUP though.
I've also demoted the build info logs to be debug level. We don't need
them in the compute image since we have other ways to determine what
code is running.
Lastly, I've demoted SIGHUP signal handling from warn to info, since
it's not really a warning event.
See https://github.com/neondatabase/cloud/issues/10880 for more details
## Problem
My benchmarks show that prometheus is not very good.
https://github.com/conradludgate/measured
We're already using it in storage_controller and it seems to be working
well.
## Summary of changes
Replace prometheus with my new measured crate in proxy only.
Apologies for the large diff. I tried to keep it as minimal as I could.
The label types add a bit of boiler plate (but reduce the chance we
mistype the labels), and some of our custom metrics like CounterPair and
HLL needed to be rewritten.
