Update audit events date range filter

What does this MR do and why?

This MR updates the audit events filter to clarify date range constraints as described in #294029 (closed).

The following key changes are made:

1. Show days selected using GlDateRangePicker.
2. Update the filter bar layout:
   • Move order by dropdown next to search input.
   • Update responsive layout for small displays.
3. Fix date buttons selecting one too many days.
4. Refactor date buttons spec.

Screenshots or screen recordings

Desktop

Before	After

Mobile

Before	After

Responsiveness

How to set up and validate locally

1. You need a GitLab Premium license.
2. View and interact with the audit events filter, shared in:
   • Instance-level [GDK_HOST]/admin/audit_logs
   • Group-level [GDK_HOST]/groups/gitlab-org/-/audit_events
   • Project-level [GDK_HOST]/gitlab-org/gitlab-shell/-/audit_events

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 #294029 (closed)