[Meta] Chart UX Improvements
We have UX improvements outstanding for a few aspects of the charting dashboard:
- Legend, Popover/Flag: https://gitlab.com/gitlab-org/gitlab-ce/issues/41783
- Popover arrows: https://gitlab.com/gitlab-org/gitlab-ce/issues/41784
- Axis labels and multiple series: https://gitlab.com/gitlab-org/gitlab-ce/issues/43632
- Fix for axis timescales: https://gitlab.com/gitlab-org/gitlab-ce/issues/43458