EE backport - Chart showing issues created per month
What does this MR do?
EE backport of: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/7874/commits#4c2a6fdc1b33d96e1c2f4be70e7c8e9a39ae3b3b
EE backport of: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/7874/commits#4c2a6fdc1b33d96e1c2f4be70e7c8e9a39ae3b3b