Implement second iteration of cycle analytics - Change in data measurement

Part of https://gitlab.com/gitlab-org/gitlab-ce/issues/22458

Measure everything that happened in the given time range, not only what's been pushed to production. With the exception of the staging and production stages.

• CHANGELOG entry added
• Documentation created/updated
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together