Update docker images to alpine:3.8

What does this MR do?

Updates alpine based Docker images created from this Repository to Alpine 3.8

Why was this MR needed?

Are there points in the code the reviewer needs to double check?

Does this MR meet the acceptance criteria?

• Documentation created/updated
• Tests
  • Added for this feature/bug
  • All builds are passing
• Branch has no merge conflicts with master (if you do - rebase it please)

What are the relevant issue numbers?

Closes #3418 (closed)