Replace old image with SVG for empty MR state

What does this MR do and why?

Replace old image with SVG for empty MR state. Closes #340599 (closed)

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Create an empty MR in any project and navigate to it.

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.