fix: collapse nested if-let flagged by clippy on windows

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

Author: Lewis-E

crates/datadog-trace-agent/src/mini_agent.rs

@@ -277,10 +277,10 @@ impl MiniAgent {
                     error!("TCP accept loop failed during shutdown: {e:?}");
                 }
                 #[cfg(all(windows, feature = "windows-pipes"))]
-                if let Some(h) = pipe_handle.as_mut() {
-                    if let Err(e) = h.await {
-                        error!("Named pipe accept loop failed during shutdown: {e:?}");
-                    }
+                if let Some(h) = pipe_handle.as_mut()
+                    && let Err(e) = h.await
+                {
+                    error!("Named pipe accept loop failed during shutdown: {e:?}");
                 }
                 // Now all handlers have written to the channels. Force-flush
                 // the stats flusher.