Use Usage Statistics Component in Statistics Seats Card

What does this MR do and why?

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

This MR is related to https://gitlab.com/gitlab-org/gitlab/-/issues/415698, and is part of a multi-step work (to ease the review work, hopefully).

Description	MR
Introduce new Usage Statistics Component	!125568 (closed)
Prepare Statistics Seats Card for new statistics card component	!125573 (merged)
Use Usage Statistics Component in Statistics Seats Card	👈 you are here

You can find the exploratory MR here: !125381 (closed)

In this MR we are:

1. introducing a semi-general-purpose component that will display statistics related to Seats usage (and Addons usage) (from !125568 (closed) – closed because of delayed review)
2. introducing the new component specific for Subscription Statistics (re-using the one introduced in the first MR)
3. rendering it based on the FF enableHamiltonInUsageQuotasUi
4. adding specs for the new component

Note that:

• Screnshots are for illustration purposes only. This MR includes no visual changes
• This MR only concerns one of the cards. The other will be changed in the context of: https://gitlab.com/gitlab-org/gitlab/-/issues/411951 and will have an adequate height

Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

This MR usually requires CustomersDot running, but it should be possible to validate it via CustomersDot Staging.

• Make sure to have the following env variables set up, before starting gdk
  • CUSTOMER_PORTAL_URL to https://customers.staging.gitlab.com
  • GITLAB_SIMULATE_SAAS to true
  • GITLAB_LICENSE_MODE to test
• Create a Group
• Buy a Subscription
• Visit /groups/<your-namespace-name>/-/usage_quotas#seats-quota-tab
• Enable enable_hamilton_in_usage_quotas_ui FF (globally, or for your group)

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.