Wrap single lines of code; horizontally scroll multi-line code blocks

What does this MR do?

Original problem: code blocks were wrapping in issue body

• Multi-line code blocks (```) should scroll horizontally
• Single lines of code (`) should wrap

Why was this MR needed?

Inconsistent scrolling vs wrapping behavior

What are the relevant issue numbers?

Closes #19619 (closed)

Screenshots (if relevant)