remove GLModel from base class

- only 2 gizmo use cone

(cherry picked from commit prusa3d/PrusaSlicer@3c7390e34e)
(cherry picked from commit 4647fc49ef5b925432e087252f32a6601d0410da)

src/slic3r/GUI/Gizmos/GLGizmoBase.hpp

@@ -123,9 +123,6 @@ protected:
     bool m_first_input_window_render;
     mutable std::string m_tooltip;
     CommonGizmosDataPool* m_c;
-    GLModel m_cone;
-    GLModel m_cylinder;
-    GLModel m_sphere;
 
     bool m_is_dark_mode = false;