Revert milestone filter behavior for "any"
What does this MR do?
Changes meaning of milestone=any
back to require a milestone.
Addresses regression https://gitlab.com/gitlab-org/gitlab-ce/issues/65676 by reverting the changes from https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/14586.
CE-backport: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/31583
Edited by Coung Ngo