issues: Reword some paragraphs on security support status and coverage

Link: https://lists.debian.org/debian-security/2023/05/msg00010.html

added 2 commits

• b08f7431 - issues: Drop section on OpenJDK 21
• 2c3ed353 - issues: Simplify wording about Go and Rust ecosystem packages

Compare with previous version

Wording looks good to me.

Looks good!

merged