Drop DEBUG_REQUESTS environment variable

This hasn't been used in years, and I'm not sure it would be helpful
with current production traffic (concurrent requests can interleave
their output). We should be able to build out something more targed with
`tracing`.

Author: jtgeibel

src/middleware.rs

@@ -50,10 +50,6 @@ pub fn build_middleware(app: Arc<App>, endpoints: RouteBuilder) -> MiddlewareBui
         m.add(Debug);
     }
 
-    if env::var_os("DEBUG_REQUESTS").is_some() {
-        m.add(DebugRequest);
-    }
-
     if env::var_os("LOG_CONNECTION_POOL_STATUS").is_some() {
         m.add(LogConnectionPoolStatus::new(&app));
     }

src/middleware/debug.rs

@@ -22,7 +22,7 @@ impl Middleware for Debug {
 }
 
 #[derive(Clone, Copy, Debug)]
-pub struct DebugRequest;
+struct DebugRequest;
 
 impl Middleware for DebugRequest {
     fn before(&self, req: &mut dyn RequestExt) -> BeforeResult {