chore(local_proxy): reduce some startup logging (#9798)

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

proxy/src/jemalloc.rs

@@ -38,7 +38,7 @@ where
 
 impl MetricRecorder {
     pub fn new() -> Result<Self, anyhow::Error> {
-        tracing::info!(
+        tracing::debug!(
             config = config::malloc_conf::read()?,
             version = version::read()?,
             "starting jemalloc recorder"