Update review started icon in MR sidebar

What does this MR do and why?

• Updates icon for Reviewer started review icon
• Use gray fill color to make it stand out more from commented
• Slack conversation

Screenshots or screen recordings

Before	After

How to set up and validate locally

Project > merge request > start a review

Links

• ✂️ UX Paper Cuts 17.3 → Dark mode - Design Support (#452231 - closed)