[sgl-router] refactor - move policy-required states under src/state (#40272)

Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

experimental/sgl-router/tests/proxy/common/cache_aware_fixture.rs

@@ -7,8 +7,8 @@
 //! built-in V4 chat formatter — the engine-equivalent path — with no template fixture.
 
 use sgl_router::config::{
-    ActiveLoadConfig, CacheAwareConfig, Config, DiscoveryBackend, ModelConfig, ObservabilityConfig,
-    PolicyKind, ProxyConfig, ServerConfig, StaticUrlsDiscoveryConfig,
+    CacheAwareConfig, Config, DiscoveryBackend, InflightLoadConfig, ModelConfig,
+    ObservabilityConfig, PolicyKind, ProxyConfig, ServerConfig, StaticUrlsDiscoveryConfig,
 };
 
 pub const MODEL: &str = "deepseek-v4-tiny";
@@ -42,6 +42,6 @@ pub fn config() -> Config {
             urls: vec!["http://placeholder:0".into()],
         }),
         proxy: ProxyConfig::default(),
-        active_load: ActiveLoadConfig::default(),
+        router_inflight_load: InflightLoadConfig::default(),
     }
 }