Use get_cursor_shape for identifying the cursor shape in AnimationTimelineEdit

get_cursor_shape() is used in cases where a Control displays different cursors in different areas.
There is no need to set the default cursor shape on every mouse move event.

editor/animation_track_editor.h

@@ -121,6 +121,8 @@ public:
 
 	void set_hscroll(HScrollBar *p_hscroll);
 
+	virtual CursorShape get_cursor_shape(const Point2 &p_pos) const override;
+
 	AnimationTimelineEdit();
 };