EE: Replace direct use of Gitlab::SQL::Union with a "from_union" method
What does this MR do?
This is the EE version of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/21672 with all merge conflicts resolved.
Does this MR meet the acceptance criteria?
-
Tests added for this feature/bug -
Conforms to the code review guidelines -
Conforms to the merge request performance guidelines -
Conforms to the style guides
Edited by Yorick Peterse