Fix the sanity error reported by check_sources_and_headers.py

test/cpp/util/metrics_server.h

@@ -36,7 +36,6 @@
 #include <map>
 #include <mutex>
 
-#include "grpc/support/time.h"
 #include "src/proto/grpc/testing/metrics.grpc.pb.h"
 #include "src/proto/grpc/testing/metrics.pb.h"