Move analytics specific utils and constants

What does this MR do and why?

Move utils and constants that are specific to analytics out of the vue shared directory and into the analytics dashboard directory.

This is part of a series of MRs:

1. Move analytics utils & constants to analytics dashboard directory. 👈 YOU ARE HERE
2. Move customizable dashboard components to analytics dashboard directory. 🚧

Why? The current customizable dashboard component is not truly reusable and contains a lot of analytics domain logic and references. This component is being deprecated and replaced with a new component that's based of the new dashboard layout framework.

References

Relevant issue Deprecate the existing customizable_dashboard c... (#552056 - closed).

Screenshots or screen recordings

There should be no visual changes.

Project level dashboards

Before	After

Group level dashboards

Before	After

How to set up and validate locally

1. Checkout this MR’s branch
2. Verify that the group dashboard render correctly at [GDK_HOST]/groups/gitlab-org/-/analytics/dashboards
3. Verify that the project dashboard render correctly at [GDK_HOST]/gitlab-org/gitlab-test/-/analytics/dashboards/
4. Enable the customizable_dashboards feature at [GDK_HOST]/rails/features/
5. Navigat to project dashboards at [GDK_HOST]/gitlab-org/gitlab-test/-/analytics/dashboards/
6. Create a new dashboard or copy an existing dashboard and view it
7. Click on the Edit button and verify the customize experience

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 #552056 (closed)