Improve MR analytics dashboard table responsiveness

What does this MR do and why?

• Removes horizontal scrolling from the merge requests table to improve the column scaling for different screen sizes.
• Converts to a stacked table for md and below screen sizes.

References

Screenshots or screen recordings

Width	Before	After
1200px
800px
600px

How to set up and validate locally

• Navigate to the MR analytics dashboard for any project/group (Analyze > Analytics dashboards > Merge request analytics or use link: http://gdk.test:3000/flightjs/Flight/-/analytics/dashboards/merge_request_analytics)
• View the Merge requests table at different screen sizes

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 #577323 (closed)