network_manager: Remove unused restart code

Change-Id: If082467ddd0ed8df6dc6f1c7f96c9028bffac58b
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/test/mock_network_manager.hpp b/test/mock_network_manager.hpp
index 9e27c9c..dce1b36 100644
--- a/test/mock_network_manager.hpp
+++ b/test/mock_network_manager.hpp
@@ -45,7 +45,7 @@
                 std::make_pair(std::move(interface), std::move(intf)));
         }
     }
-    MOCK_METHOD1(restartSystemdUnit, void(const std::string& service));
+
     MOCK_METHOD(void, reloadConfigs, (), (override));
 };