Add a `Last 7 days` option for Cycle Analytics view

What does this MR do?

This MR suggests an addition to Cycle Analytics view: a 7 days option. The 30 days view is still the one shown by default.
(The MR also adds feature specs for pipeline summary that were missing)

Why was this MR needed?

Currently, the Cycle Analytics view show data for the last 30 days or 90 days.
A 30 days view is too large for us, so I built a quick thing for my team showing almost the same data but for a week only.
I felt this could be useful for other teams, doing weekly meetings/planning/sprints/wathever-you-name-it.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• 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

What are the relevant issue numbers?

Closes #36300 (closed)