proxy fix wake compute rate limit (#7902)

## Problem

We were rate limiting wake_compute in the wrong place

## Summary of changes

Move wake_compute rate limit to after the permit is acquired. Also makes
a slight refactor on normalize, as it caught my eye

proxy/src/auth/backend.rs

@@ -35,7 +35,7 @@ use crate::{
     },
     stream, url,
 };
-use crate::{scram, EndpointCacheKey, EndpointId, Normalize, RoleName};
+use crate::{scram, EndpointCacheKey, EndpointId, RoleName};
 
 /// Alternative to [`std::borrow::Cow`] but doesn't need `T: ToOwned` as we don't need that functionality
 pub enum MaybeOwned<'a, T> {