Search > code results UI tweaks

What does this MR do and why?

• Removes link icon on line hover (we don't do this on other blobs anymore)
• Removes extra margin in file content
• Fixes border radius bugs

What does this MR not do?

Fix the Showing x results... and branch/project alignment (fixed in Fix alignment for global search filter row (!151503 - merged))

Screenshots or screen recordings

Before	After

How to set up and validate locally

• Enable elasticsearch
• Go to global search (http://127.0.0.1:3000/search)
• Search something and filter results by code

Links

• ✂️ UX Paper Cuts 17.0 → Search and Filter (#444717 - closed)