Add anon users toggle to product analytics dashboards

What does this MR do and why?

Adds an exclude anonymous users toggle to product analytics and custom user analytics dashboards for MVC: Filter by `user_id_type` on default dashbo... (#421328 - closed).

When enabled this excludes anonymous users from tracked events queries.

This MR also improves the filters layout on small viewports. It moves the date picker's tooltip icon to be inline with its inputs.

Note: This is an experimental feature hidden behind a default off feature flag.

Screenshots or screen recordings

New anonymous users toggle

Before	After (disabled)	After (enabled)

Small viewport layout changes

Before	After

How to set up and validate locally

1. You need a GitLab Ultimate license.
2. Follow the internal event tracking docs to setup your local test environment.
3. Follow the latest GDK docs to setup Product Analytics.
4. Enable Experiment and Beta features and Product Analytics feature at Group > Settings > General > Permissions and group features.
5. Set up product analytics by clicking on the button at Project > Analytics > Analytics dashboards.
6. View one of the built-in dashboards and click on the Exclude anonymous users toggle to enable it.
7. Using your browser network tab verify that segments: ["TrackedEvents.knownUsers"] is sent with each Tracked Events query load request.

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.

Related to #421328 (closed)