chore: cleanup garbage code (#29770)

experimental/sgl-router/tests/proxy/pd_pool_isolation.rs

@@ -13,7 +13,7 @@
 //!   (existing code path; pinned here so a future PD wiring change
 //!   doesn't silently swap codes).
 //! * A PD-disagg model with both pools healthy → request flows to the
-//!   prefill worker (smoke; the decode worker MUST NOT be selected for
+//!   prefill worker (sanity check; the decode worker MUST NOT be selected for
 //!   the chat route).
 
 use axum::body::Body;