util/prim_restart: revert part of bad fix

util/prim_restart: revert part of bad fix

When drawing using util_translate_prim_restart_ib, zink explicitly
ignores pipe_draw_start_count_bias::start, because
util_translate_prim_restart_ib used to create a new index-buffer without
padding at the start.

This makes a lot of sense, because creating a padded index buffer is
just wasteful.

So let's walk back on the choice of starting to pad the output buffer.

Fixes: 1272c2e0524 ("util/prim_restart: fix util_translate_prim_restart_ib")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/4851
Reviewed-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11059>