proxy: Rename RequestMonitoring to RequestContext (#9805)

## Problem

It is called context/ctx everywhere and the Monitoring suffix needlessly
confuses with proper monitoring code.

## Summary of changes

* Rename RequestMonitoring to RequestContext
* Rename RequestMonitoringInner to RequestContextInner

proxy/src/auth/flow.rs

@@ -11,7 +11,7 @@ use tracing::info;
 use super::backend::ComputeCredentialKeys;
 use super::{AuthError, PasswordHackPayload};
 use crate::config::TlsServerEndPoint;
-use crate::context::RequestMonitoring;
+use crate::context::RequestContext;
 use crate::control_plane::AuthSecret;
 use crate::intern::EndpointIdInt;
 use crate::sasl;
@@ -32,7 +32,7 @@ pub(crate) struct Begin;
 /// Use [SCRAM](crate::scram)-based auth in [`AuthFlow`].
 pub(crate) struct Scram<'a>(
     pub(crate) &'a scram::ServerSecret,
-    pub(crate) &'a RequestMonitoring,
+    pub(crate) &'a RequestContext,
 );
 
 impl AuthMethod for Scram<'_> {