Don't prompt to 'Save game as' when saving (#16819)

After loading a saved game and choosing 'Save game', the 'Save game as' window would open the first time every time after loading the save.
Now, it will be saved using the existing save path, except when an autosave is loaded which the player probably doesn't want to overwrite.

src/openrct2-ui/windows/LoadSave.cpp

@@ -1000,6 +1000,7 @@ static void WindowLoadsaveSelect(rct_window* w, const char* path)
             {
                 gScenarioSavePath = pathBuffer;
                 gCurrentLoadedPath = pathBuffer;
+                gIsAutosaveLoaded = false;
                 gFirstTimeSaving = false;
 
                 window_close_by_class(WindowClass::Loadsave);