vbo/dlist: reallocate the vertex buffer on vertex upgrade

vbo/dlist: reallocate the vertex buffer on vertex upgrade

upgrade_vertex copies save->copied.nr vertices to the vertex buffer,
so we need to make sure it has enough space to accomodate them.

This commit also drops the usage of COPY_CLEAN_4V_TYPE_AS_UNION in
this function because it always writes 4-components for all attributes,
but our buffer might be smaller. Instead, only write the needed
components.

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/5353
Fixes: cc57156dce0 ("vbo/dlist: rework vertex_store management")
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12849>