proxy: remove dead code (#8847)

By marking everything possible as pub(crate), we find a few dead code
candidates.

proxy/src/rate_limiter/limit_algorithm/aimd.rs

@@ -10,17 +10,17 @@ use super::{LimitAlgorithm, Outcome, Sample};
 ///
 /// Reduces available concurrency by a factor when load-based errors are detected.
 #[derive(Clone, Copy, Debug, serde::Deserialize, PartialEq)]
-pub struct Aimd {
+pub(crate) struct Aimd {
     /// Minimum limit for AIMD algorithm.
-    pub min: usize,
+    pub(crate) min: usize,
     /// Maximum limit for AIMD algorithm.
-    pub max: usize,
+    pub(crate) max: usize,
     /// Decrease AIMD decrease by value in case of error.
-    pub dec: f32,
+    pub(crate) dec: f32,
     /// Increase AIMD increase by value in case of success.
-    pub inc: usize,
+    pub(crate) inc: usize,
     /// A threshold below which the limit won't be increased.
-    pub utilisation: f32,
+    pub(crate) utilisation: f32,
 }
 
 impl LimitAlgorithm for Aimd {