Draft: Remove Cube.js from Product Analytics

What does this MR do and why?

DO NOT MERGE UNTIL: https://gitlab.com/gitlab-org/gitlab/-/issues/558072+ is complete

As part of the deprecation of Product Analytics, we need to remove the Cube.js package, and all references within the codebase.

This MR specifically:

• Removes Cube.js from node packages and webpack references
• Removes the frontend Cube.js data source and associated tests
• Updates the test mock data to use a different data source for tests

References

• https://gitlab.com/groups/gitlab-org/-/epics/17677+
• https://gitlab.com/gitlab-org/gitlab/-/issues/560954+

Screenshots or screen recordings

Before	After

How to set up and validate locally

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Related to #560954