Refactor snippets search

If we found 1000 snippets it will call chunk_snippet for 1000 snippets then will paginate it. It's a bit silly

https://gitlab.com/gitlab-org/gitlab-ce/blob/master/lib/gitlab/snippet_search_results.rb#L43

/cc @dzaporozhets

Yes we should refactor it

mentioned in merge request !2729 (merged)

Status changed to closed by merge request !2729 (merged)