mesa: set pipe_draw_info::index::resource directly and remove gl_bo

mesa: set pipe_draw_info::index::resource directly and remove gl_bo

The motivation is to remove branching from prepare_indexed_draw
and remove the unsafe hack in vbo_save_playback_vertex_list.

There is some duplication that is not identical in all 3 cases.

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20287>