SITL: don't use adjusted terrain in SITL

libraries/SITL/SIM_Aircraft.cpp

@@ -111,8 +111,8 @@ float Aircraft::ground_height_difference() const
     if (sitl &&
         terrain != nullptr &&
         sitl->terrain_enable &&
-        terrain->height_amsl(home, h1) &&
-        terrain->height_amsl(location, h2)) {
+        terrain->height_amsl(home, h1, false) &&
+        terrain->height_amsl(location, h2, false)) {
         h2 += local_ground_level;
         return h2 - h1;
     }

libraries/SITL/SIM_Ship.cpp

@@ -204,7 +204,7 @@ void ShipSim::send_report(void)
 #if AP_TERRAIN_AVAILABLE
     auto terrain = AP::terrain();
     float height;
-    if (terrain != nullptr && terrain->enabled() && terrain->height_amsl(loc, height)) {
+    if (terrain != nullptr && terrain->enabled() && terrain->height_amsl(loc, height, false)) {
         alt_mm = height * 1000;
     }
 #endif