Test-only change: Don't update actuator_force in Advance in TestActuator.

Actuators update actuator_force in compute and not in advance.

PiperOrigin-RevId: 581985081
Change-Id: I013d6c4f0888ee8e25df15a6f58c9e3412d33ceb

test/engine/engine_plugin_test.cc

@@ -19,6 +19,8 @@
 
 #include <cstdint>
 #include <sstream>
+#include <string>
+#include <string_view>
 #include <vector>
 
 #include <gmock/gmock.h>
@@ -170,11 +172,6 @@ class TestActuator : public BaseTestPlugin {
     WriteActuatorForce();
   }
 
-  void Advance() {
-    BaseTestPlugin::Advance();
-    WriteActuatorForce();
-  }
-
  private:
   mjtNum multiplier;
   std::vector<mjtNum*> actuators;