NB: No functional changes
test_efl_anim_interpolator: delete animation event callback on window delete
elementary_test Efl.Animation.Interpolator test performs Invalid
memory access if the window is closed during the animation. This can
lead to elm_test crashing after the main window is closed.
In order to avoid this invalid memory access, when the window gets
deleted we can delete the efl_event_callback so that the event does
not fire while the window is being deleted.